View Filing Data

Accounts Receivable [Member] | Number of Customers [Member]

11.20%

Organization Consolidation and Presentation of Financial Statements [Line Items]

Organization Consolidation and Presentation of Financial Statements [Line Items]

10.00%

Revenues [Member]

Revenues [Member] | Number of Customers [Member] | Customer concentration risk [Member]

40.40%

46.40%

44.60%

Organization Consolidation and Presentation of Financial Statements [Line Items]

Labor employees covered by collective bargaining agreements [Member] | Labor Force Concentration Risk [Member]

10.00%

Organization Consolidation and Presentation of Financial Statements [Line Items]

Sales Revenue, Net [Member] | TD customer [Member] | Customer concentration risk [Member]

91.00%

Organization Consolidation and Presentation of Financial Statements [Line Items]

Restatement Adjustment [Member]

10.70%

Organization Consolidation and Presentation of Financial Statements [Line Items]

Retained Earnings (Accumulated Deficit)

$ 200

Estimate Adjustment [Member]

Organization Consolidation and Presentation of Financial Statements [Line Items]

Cost Estimate Revision Gross Margin Increase (Decrease) Percentage

(0.70%)

(0.20%)

0.50%

Operating Income (Loss)

$ (10,400)

$ (2,600)

$ 5,900

Net Income (Loss) Attributable to Parent

$ (6,200)

$ (1,400)

$ 3,600

Earnings Per Share, Diluted

$ (0.38)

$ (0.08)

$ 0.17

[1]	Results for the fourth quarter of 2017 include a net Tax Act benefit of $7.8 million, or $0.48 and $0.47 per basic and diluted share, respectively. See further discussion in Note 10 — Income Taxes to our Financial Statements.

Acquisitions (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Oct. 28, 2016
Business Acquisition [Line Items]
Goodwill	$ 46,994	$ 46,781
Western Pacific Enterprises [Member]
Business Acquisition [Line Items]
Total consideration, net of net asset adjustments			$ 11,283
Accounts receivable, net			20,249
Costs and estimated earnings in excess of billings on uncompleted contracts			1,610
Other current assets			8
Property and equipment			4,108
Intangible assets			0
Accounts payable			(10,125)
Billings in excess of costs and estimated earnings on uncompleted contracts			(3,020)
Other current liabilities			(2,294)
Net identifiable assets			10,536
Unallocated intangible assets			747
Goodwill			$ 0
Scenario, Previously Reported [Member] \| Western Pacific Enterprises [Member]
Business Acquisition [Line Items]
Total consideration, net of net asset adjustments	0
Accounts receivable, net	0
Costs and estimated earnings in excess of billings on uncompleted contracts	0
Other current assets	0
Property and equipment	46
Intangible assets	501
Accounts payable	0
Billings in excess of costs and estimated earnings on uncompleted contracts	0
Other current liabilities	0
Net identifiable assets	547
Unallocated intangible assets	(747)
Goodwill	200
Restatement Adjustment [Member] \| Western Pacific Enterprises [Member]
Business Acquisition [Line Items]
Total consideration, net of net asset adjustments	11,283
Accounts receivable, net	20,249
Costs and estimated earnings in excess of billings on uncompleted contracts	1,610
Other current assets	8
Property and equipment	4,154
Intangible assets	501
Accounts payable	(10,125)
Billings in excess of costs and estimated earnings on uncompleted contracts	(3,020)
Other current liabilities	(2,294)
Net identifiable assets	11,083
Unallocated intangible assets	0
Goodwill	$ 200

Acquisitions (Details Textual) - USD ($) $ in Thousands		1 Months Ended		12 Months Ended
Acquisitions (Details Textual) - USD ($) $ in Thousands	Apr. 13, 2015	Oct. 28, 2016	Nov. 24, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Business Acquisition [Line Items]
Payments to Acquire Businesses, Net of Cash Acquired				$ 0	$ 12,056	$ 13,087
Other Nonoperating Income					$ 1,400
Other Nonoperating Expense				2,300
E.S. Boulos Company [Member]
Business Acquisition [Line Items]
Business Combination, Consideration Transferred, Total	$ 11,400
High Country Line Construction Inc [Member]
Business Acquisition [Line Items]
Business Combination, Consideration Transferred, Total			$ 1,700
Business Acquisition, Transaction Costs			200
Finite-lived Intangible Assets Acquired			300
High Country Line Construction Inc [Member] \| Goodwill [Member]
Business Acquisition [Line Items]
Goodwill, Acquired During Period			$ 200
Western Pacific Enterprises [Member]
Business Acquisition [Line Items]
Business Acquisition, Transaction Costs				400
Goodwill, Acquired During Period				200
Payments to Acquire Businesses, Net of Cash Acquired		$ 12,100
Business Combination, Contingent Consideration, Liability				2,200
Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Liability		800
Escrow Deposit		$ 1,900
Finite-lived Intangible Assets Acquired				$ 500

Accounts Receivable (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Accounts Receivable [Line Items]
Contract receivables	$ 231,808	$ 200,732
Contract retainages	42,732	32,486
Other	9,073	1,856
Accounts receivable, gross current	283,613	235,074
Less: Allowance for doubtful accounts	(605)	(432)
Accounts receivable, net current	$ 283,008	$ 234,642

Accounts Receivable (Details 1) - USD ($) $ in Thousands	12 Months Ended
Accounts Receivable (Details 1) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accounts Receivable [Line Items]
Balance at beginning of period	$ 432	$ 376	$ 1,179
Less: Reduction in (provision for) allowances	(263)	(146)	528
Less: Write offs, net of recoveries	92	90	275
Change in foreign currency translation	(2)	0	0
Balance at end of period	$ 605	$ 432	$ 376

Contracts in Process (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Contracts in Process [Line Items]
Costs and estimated earnings on uncompleted contracts	$ 1,978,981	$ 2,194,695
Less: Billings to date	1,929,640	2,167,066
Net asset position for contracts in process	$ 49,341	$ 27,629

Contracts in Process (Details 1) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Contracts in Process [Line Items]
Costs and estimated earnings in excess of billings on uncompleted contracts	$ 78,260	$ 69,950
Billings in excess of costs and estimated earnings on uncompleted contracts	(28,919)	(42,321)
Net asset position for contracts in process	$ 49,341	$ 27,629

Property and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 379,475	$ 364,357
Less: Accumulated depreciation and amortization	(231,391)	(209,466)
Property, Plant and Equipment, Net	148,084	154,891
Land [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 7,733	5,468
Estimated Useful Life	0 years
Building and Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 22,718	21,660
Building and Improvements [Member] \| Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Life	39 years
Building and Improvements [Member] \| Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Life	3 years
Construction Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 340,060	329,299
Construction Equipment [Member] \| Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Life	12 years
Construction Equipment [Member] \| Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Life	3 years
Office Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 8,964	$ 7,930
Office Equipment [Member] \| Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Life	10 years
Office Equipment [Member] \| Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Life	3 years

Property and Equipment (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Depreciation	$ 38,077	$ 38,236	$ 37,458

Goodwill and Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Schedule Of Intangible Assets And Goodwill [Line Items]
Goodwill gross carrying amount	$ 46,994	$ 46,781
Goodwill accumulated amortization	0	0
Goodwill net carrying amount	46,994	46,781
Accumulated Amortization	5,183	4,684
Amortizable intangible assets net carrying amount	1,778
Intangible Assets, Gross (Excluding Goodwill)	16,035	16,250
Intangible Assets, Net (Excluding Goodwill)	10,852	11,566
T&D [Member]
Schedule Of Intangible Assets And Goodwill [Line Items]
Goodwill gross carrying amount	40,224	40,224
Goodwill accumulated amortization	0	0
Goodwill net carrying amount	40,224	40,224
C&I [Member]
Schedule Of Intangible Assets And Goodwill [Line Items]
Goodwill gross carrying amount	6,770	6,557
Goodwill accumulated amortization	0	0
Goodwill net carrying amount	6,770	6,557
Backlog [Member]
Schedule Of Intangible Assets And Goodwill [Line Items]
Amortizable intangible assets gross carrying amount	989	989
Accumulated Amortization	989	989
Amortizable intangible assets net carrying amount	0	0
Customer Relationships [Member]
Schedule Of Intangible Assets And Goodwill [Line Items]
Amortizable intangible assets gross carrying amount	5,277	5,266
Accumulated Amortization	4,069	3,590
Amortizable intangible assets net carrying amount	1,208	1,676
Trade Names [Member]
Schedule Of Intangible Assets And Goodwill [Line Items]
Amortizable intangible assets gross carrying amount	695	695
Accumulated Amortization	125	79
Amortizable intangible assets net carrying amount	570	616
Indefinite-lived Intangible Assets	9,074	8,556
Intangible Assets, Gross (Excluding Goodwill)	0	0
Intangible Assets, Net (Excluding Goodwill)	9,074	8,556
Unallocated Intangible Assets [Member]
Schedule Of Intangible Assets And Goodwill [Line Items]
Amortizable intangible assets gross carrying amount	0	744
Accumulated Amortization	0	26
Amortizable intangible assets net carrying amount	$ 0	$ 718

Goodwill and Intangible Assets (Details 1) $ in Thousands	Dec. 31, 2017 USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
2018	$ 443
2019	137
2020	137
2021	137
2022	137
Thereafter	787
Total	$ 1,778

Goodwill and Intangible Assets (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Line Items]
Amortization of Intangible Assets	$ 499	$ 886	$ 571
Western Pacific Enterprises [Member] \| High Country Line Construction Inc [Member]
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Line Items]
Goodwill, Period Increase (Decrease)	$ 200
Western Pacific Enterprises [Member] \| Maximum [Member]
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	12 years 6 months
Trade Names [Member]
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Line Items]
Estimated useful life	15 years
Customer Relationships [Member]
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Line Items]
Estimated useful life	12 years

Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Other Current Liabilities [Line Items]
Payroll and incentive compensation	$ 9,146	$ 16,101
Union dues and benefits	12,494	10,261
Profit sharing and thrift plan	443	2,004
Taxes, other than income taxes	6,807	7,639
Other	6,148	6,377
Other current liabilities, total	$ 35,038	$ 42,382

Debt (Details Textual) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
Debt (Details Textual) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Letters of Credit Outstanding, Amount		$ 20.9	$ 23.7
Long-term Line of Credit		79.0	59.1
Debt Issuance Costs, Line of Credit Arrangements, Net		$ 0.8
Debt Instrument Covenant Leveraged Debt Ratio Restriction		2.25
Insurance Programe Obligations [Member]
Debt Instrument [Line Items]
Letters of Credit Outstanding, Amount		$ 17.6	17.6
Contract Performance Obligations [Member]
Debt Instrument [Line Items]
Letters of Credit Outstanding, Amount		$ 3.3	$ 6.1
Maximum [Member]
Debt Instrument [Line Items]
Leveraged debt ratio	3.0
Leverage Coverage Ratio Expansion	3.5
Maximum [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage		0.375%
Maximum [Member] \| Performance letters of credit [Member]
Debt Instrument [Line Items]
Letter of credit fee (as a percent)		1.125%
Maximum [Member] \| Non-performance Letters Of Credit [Member]
Debt Instrument [Line Items]
Interest rate margin (as a percent)		2.125%
Maximum [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Interest rate margin (as a percent)		2.00%
Maximum [Member] \| Base Rate [Member]
Debt Instrument [Line Items]
Interest rate margin (as a percent)		1.00%
Minimum [Member]
Debt Instrument [Line Items]
Interest coverage ratio	3.0
Minimum [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage		0.20%
Minimum [Member] \| Performance letters of credit [Member]
Debt Instrument [Line Items]
Letter of credit fee (as a percent)		0.625%
Minimum [Member] \| Non-performance Letters Of Credit [Member]
Debt Instrument [Line Items]
Interest rate margin (as a percent)		1.125%
Minimum [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Interest rate margin (as a percent)		1.00%
Minimum [Member] \| Base Rate [Member]
Debt Instrument [Line Items]
Interest rate margin (as a percent)		0.00%
Swing line Loans [Member] \| Facility [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 25.0
Syndicated Credit Agreement [Member] \| Facility [Member]
Debt Instrument [Line Items]
Option to increase borrowing capacity	$ 100.0
Maximum borrowing capacity	$ 250.0
Syndicated Credit Agreement [Member] \| Facility [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 175.0
Credit Agreement [Member]
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate		2.07%
Credit Agreement [Member] \| Facility [Member]
Debt Instrument [Line Items]
Percentage of Capital Stock From Direct Foreign Subsidiaries	65.00%
Maximum Acquisition Consideration Under Credit Agreement		$ 50.0
Credit Agreement [Member] \| Foreign Revolving Loans and Letters of Credit [Member] \| Facility [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 50.0

Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
Income Taxes (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income before income taxes
Federal	$ 33,830	$ 39,419	$ 45,456
Foreign	(9,190)	(1,074)	(1,157)
Income before income taxes	$ 24,640	$ 38,345	$ 44,299

Income Taxes (Details 1) - USD ($) $ in Thousands	12 Months Ended
Income Taxes (Details 1) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current
Federal	$ 7,020	$ 9,838	$ 12,433
State	1,557	2,871	3,006
Current Income Tax Expense (Benefit)	8,577	12,709	15,439
Deferred
Federal	(1,453)	2,491	1,553
Foreign	(875)	481	(272)
State	(2,763)	1,233	277
Deferred Income Tax Expense (Benefit)	(5,091)	4,205	1,558
Income tax expense	$ 3,486	$ 16,914	$ 16,997

Income Taxes (Details 2)	12 Months Ended
Income Taxes (Details 2)	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Differences between the U.S. federal statutory rate and the Company's effective tax rate for continuing operations
U.S federal statutory rate	35.00%	35.00%	35.00%
Deferred balance adjustments due to Tax Act, net	(31.60%)	0.00%	0.00%
State income taxes, net of U.S. federal income tax expense	5.30%	5.20%	4.60%
Change in valuation allowance	6.40%	1.60%	0.00%
Domestic production/manufacturing deduction	(1.60%)	(1.90%)	(2.40%)
Tax differential on foreign earnings	3.20%	0.60%	0.30%
Deferred state tax adjustments, net	(2.40%)	1.60%	0.00%
Non-deductible meals and entertainment	1.70%	1.00%	0.60%
Stock compensation excess tax benefits	(3.10%)	0.00%	0.00%
Uncertain tax positions	2.00%	0.00%	(0.40%)
Provision to return adjustments, net	(0.30%)	0.80%	0.50%
Other income, net	(0.50%)	0.20%	0.20%
Effective rate	14.10%	44.10%	38.40%

Income Taxes (Details 3) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred income tax assets:
Self insurance reserves	$ 4,555	$ 6,670
Contract loss reserves	317	257
Stock-based awards	1,571	2,554
Bonus	590	2,908
Non-U.S. operating loss	2,173	595
Non-U.S. deferred income tax assets, net	773	0
Other	1,359	1,652
Total deferred income tax assets before valuation allowances	11,338	14,636
Less: valuation allowances	(2,173)	(595)
Total deferred income tax assets	9,165	14,041
Deferred income tax liabilities:
Property and equipment - tax over book depreciation	(18,792)	(26,664)
Intangible assets - tax over book amortization	(2,186)	(3,592)
Non-U.S. deferred income tax liabilities	0	(91)
Other	(1,639)	(2,259)
Total deferred income tax liabilities	(22,617)	(32,606)
Net deferred income taxes	$ (13,452)	$ (18,565)

Income Taxes (Details 4) - USD ($) $ in Thousands	12 Months Ended
Income Taxes (Details 4) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of the beginning and ending liabilities for unrecognized tax benefits
Balance at beginning of period	$ 301	$ 425
Gross increases in current period tax positions	67	100
Gross increases in prior period tax positions	441	0
Reductions in tax positions due to lapse of statutory limitations	(22)	(12)
Settlements with taxing authorities	0	(243)
Balance at end of period	787	301
Accrued interest and penalties at end of period	0	31
Total liability for unrecognized tax benefits	$ 787	$ 301

Income Taxes (Details Textual) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Income Taxes (Details Textual) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Taxes [Line Items]
Significant change in unrecognized tax benefits is reasonably possible amount of unrecorded benefit	$ 0.1		$ 0.1
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent			35.00%	35.00%	35.00%
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount	$ 7.8		$ 7.8
Scenario, Plan [Member]
Income Taxes [Line Items]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent		21.00%

Commitments and Contingencies (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Roll forward of activity in insurance reserves
Balance at beginning of period	$ 42,584	$ 36,967	$ 39,480
Net increases in reserves	22,938	25,139	15,686
Net payments made	(20,159)	(19,522)	(18,199)
Balance at end of period	$ 45,363	$ 42,584	$ 36,967

Commitments and Contingencies (Details Textual) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Other Commitments [Line Items]
Outstanding Performance Bonds	$ 497.0
Estimated Cost to Complete Bonded Projects	144.5
Purchase Commitment, Remaining Minimum Amount Committed	12.3
Insurance Claims [Member]
Other Commitments [Line Items]
Loss Contingency Insurance Expense	29.5	$ 25.6	$ 23.6
Maximum [Member]
Other Commitments [Line Items]
Loss Contingency Insurance Policy Deductible for Each Line of Coverage Excluding Wildfire and Health	1.0
Loss Contingency Insurance Policy Deductible for Wildfire	2.0
Loss Contingency Health Insurance Deductible For Qualified Individuals	$ 0.2

Lease Obligations (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Capital Lease Obligations
2018	$ 1,185
2019	1,185
2020	1,185
2021	360
2022	0
Thereafter	0
Total minimum lease payments	3,915
Interest	(200)
Net present of minimum lease payments	3,715
Less: Current portion of capital lease obligations	1,086	$ 1,085
Long-term capital lease obligations	2,629	$ 3,833
Operating Lease Obligations
2018	3,599
2019	2,885
2020	2,187
2021	1,582
2022	1,014
Thereafter	564
Total minimum lease payments	$ 11,831

Lease Obligations (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Capital Leases, Balance Sheet, Assets by Major Class, Net, Total	$ 3,700	$ 5,000
Capital Lease Obligations, Current	1,086	1,085
Capital Lease Obligations	3,700
Operating Leases, Rent Expense, Net	$ 44,600	$ 44,900	$ 57,200

Stock-Based Compensation (Details) - Stock Option [Member] - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options, Outstanding beginning	245,717	730,605	1,008,781
Options, Exercised	(79,797)	(443,283)	(267,440)
Options, Forfeited		(933)	(1,290)
Options, Expired		(40,672)	(9,446)
Options, Outstanding ending	165,920	245,717	730,605
Weighted-Average Exercise Price, Outstanding beginning	$ 19.82	$ 16.40	$ 13.87
Weighted-Average Exercise Price, Exercised	15.43	14.03	7.19
Weighted-Average Exercise Price, Forfeited		24.68	23.14
Weighted Average Exercise Price, Expired		21.40	5.92
Weighted-Average Exercise Price, Outstanding ending	$ 21.92	$ 19.82	$ 16.40
Outstanding Weighted Average Remaining Contractual Term	4 years 2 months 12 days	4 years 4 months 24 days	3 years 7 months 6 days
Outstanding, Aggregate Intrinsic Value	$ 2,292	$ 4,396	$ 3,722

Stock-Based Compensation (Details 1) - Equity Option [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stock-Based Compensation
Intrinsic value of options exercised	$ 1,721	$ 7,832	$ 5,857
Fair value of options vested	$ 0	$ 372	$ 948

Stock-Based Compensation (Details 2)	12 Months Ended
Stock-Based Compensation (Details 2)	Dec. 31, 2017 $ / shares shares
Options Outstanding and Exercisable
Number Of Options (in shares) \| shares	165,920
Weighted-Average Exercise Price (in dollars per share)	$ 21.92
Weighted-Average Remaining Contractual Term	4 years 2 months 12 days
Range Of Exercise Prices From Dollars 17.18 To 17.48
Stock options outstanding
Exercise price, low end of range (in dollars per share)	$ 17.18
Exercise price, high end of range (in dollars per share)	$ 17.48
Options Outstanding and Exercisable
Number Of Options (in shares) \| shares	60,267
Weighted-Average Exercise Price (in dollars per share)	$ 17.44
Weighted-Average Remaining Contractual Term	3 years 10 months 24 days
Range Of Exercise Prices From Dollars 24.18 To 24.18
Stock options outstanding
Exercise price, low end of range (in dollars per share)	$ 24.18
Exercise price, high end of range (in dollars per share)	$ 24.18
Options Outstanding and Exercisable
Number Of Options (in shares) \| shares	44,151
Weighted-Average Exercise Price (in dollars per share)	$ 24.18
Weighted-Average Remaining Contractual Term	3 years 2 months 12 days
Range Of Exercise Prices From Dollars 24.68 To 24.68
Stock options outstanding
Exercise price, low end of range (in dollars per share)	$ 24.68
Exercise price, high end of range (in dollars per share)	$ 24.68
Options Outstanding and Exercisable
Number Of Options (in shares) \| shares	61,502
Weighted-Average Exercise Price (in dollars per share)	$ 24.68
Weighted-Average Remaining Contractual Term	5 years 2 months 12 days

Stock-Based Compensation (Details 3) - Time Vested Stock [Member] - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares, Outstanding Beginning	223,416	201,949	220,337
Shares, Granted	66,352	112,912	87,040
Shares, Vested	(99,774)	(88,301)	(102,297)
Shares, Forfeited	(1,346)	(3,144)	(3,131)
Shares, Outstanding Ending	188,648	223,416	201,949
Weighted-Average Grant Date Fair Value, Outstanding Beginning	$ 25.26	$ 24.58	$ 22.64
Weighted-Average Grant Date Fair Value, Granted	37.49	24.66	29.23
Weighted-Average Grant Date Fair Value, Vested	25.19	25.18	22.42
Weighted-Average Grant Date Fair Value, Forfeited	31.22	26.09	24.10
Weighted-Average Grant Date Fair Value, Outstanding Ending	$ 29.55	$ 25.26	$ 24.58

Stock-Based Compensation (Details 4) - Performance Shares [Member] - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares, Outstanding Beginning	144,023	143,608	126,803
Shares, Granted at target	47,454	79,661	69,978
Shares, Forfeited for performance below target	(24,873)		(3,810)
Shares, Earned for performance above target		20,650
Shares, Vested	(39,407)	(98,270)	(40,474)
Shares, Forfeited	(222)	(1,626)	(8,889)
Shares, Outstanding Ending	126,975	144,023	143,608
Weighted-Average Grant Date Fair Value, Outstanding Beginning	$ 32.92	$ 32.68	$ 26.63
Weighted-Average Grant Date Fair Value, Granted at target	47.12	28.25	38.70
Weighted-Average Grant Date Fair Value, Forfeited for performance below target	36.40		24.68
Weighted-Average Grant Date Fair Value, Earned for performance above target		31.01
Weighted-Average Grant Date Fair Value, Vested	40.15	27.74	24.68
Weighted-Average Grant Date Fair Value, Forfeited	37.22	32.96	30.87
Weighted-Average Grant Date Fair Value, Outstanding Ending	$ 35.29	$ 32.92	$ 32.68

Stock-Based Compensation (Details Textual) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Other information
Allocated Share-based Compensation Expense	$ 4.4	$ 4.7	$ 4.8
Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercisable period from date of grant	10 years
Long-Term Incentive Plan [Member]
Other information
Total unrecognized stock-based compensation expense	$ 4.4
Long-Term Incentive Plan [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum Grants Of Awards (in shares)	900,000
Restricted Awards [Member]
Other information
Total unrecognized stock-based compensation expense	$ 2.5
Weighted average vesting period	1 year 4 months 24 days
Performance awards [Member]
Other information
Total unrecognized stock-based compensation expense	$ 1.9
Weighted average vesting period	1 year 9 months 18 days
Performance awards [Member] \| Maximum [Member]
Weighted-Average Grant Date Fair Value
Potential Payout As a Percentage of Target Shares	200.00%
Internal metric-based performance awards [Member]
Other information
Share-based Compensation Arrangement by Share-based Payment Award, Award Requisite Service Period	2 years 9 months 18 days

Employee Benefit Plans (Details) - USD ($) $ in Thousands	12 Months Ended
Employee Benefit Plans (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Significant multiemployer plans
Contributions to Plan	$ 64,888	$ 53,796	$ 52,686
National Electrical Benefit Fund [Member]
Significant multiemployer plans
Contributions to Plan	9,542	9,040	6,930
Eighth District Electrical Management Pension Fund [Member]
Significant multiemployer plans
Contributions to Plan	7,908	7,519	5,598
Indiana,Kentucky,Ohio Regional Council of Carpenters Pension Fund [Member]
Significant multiemployer plans
Contributions to Plan	2,515	696	116
IBEW Local 1249 Pension Plan [Member]
Significant multiemployer plans
Contributions to Plan	1,315	630	2,042
National Electrical Annuity Plan [Member]
Significant multiemployer plans
Contributions to Plan	27,633	22,840	24,226
IBEW Local 769 Management Pension Plan [Member]
Significant multiemployer plans
Contributions to Plan	2,115	1,709	2,120
Eighth District Electrical Pension Fund Annuity Plan [Member]
Significant multiemployer plans
Contributions to Plan	4,109	4,883	3,700
All other plans [Member]
Significant multiemployer plans
Contributions to Plan	$ 9,751	$ 6,479	$ 7,954

Employee Benefit Plans (Details Textual) $ in Thousands	12 Months Ended
Employee Benefit Plans (Details Textual) $ in Thousands	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Retirement Saving Plan [Member] \| Canadian employees [Member]
Defined Contribution Plans [Line Items]
Defined Contribution Plan, Cost Recognized	$ 100
Eighth District Electrical Pension Fund [Member]
Defined Contribution Plans [Line Items]
Multiemployer Plan, Collective-Bargaining Arrangement, Required Percentage of Contributions	5.00%	5.00%	5.00%
IBEW Local 1249 Pension Plan [Member]
Defined Contribution Plans [Line Items]
Multiemployer Plan, Collective-Bargaining Arrangement, Required Percentage of Contributions			5.00%
IBEW Local 769 Management Pension Plan [Member]
Defined Contribution Plans [Line Items]
Multiemployer Plan, Collective-Bargaining Arrangement, Required Percentage of Contributions			5.00%
Multiemployer Plans, Pension [Member]
Defined Contribution Plans [Line Items]
Number Of Locals Covered Under Multiemployer Defined Plans	100
Multiemployer Plans, Pension [Member] \| Maximum [Member]
Defined Contribution Plans [Line Items]
Multiemployer Plans Red Zone Funded Status Percentage	65.00%
Multiemployer Plans Yellow Zone Funded Status Percentage	80.00%
Multiemployer Plans, Pension [Member] \| Minimum [Member]
Defined Contribution Plans [Line Items]
Multiemployer Plans Green Zone Funded Status Percentage	80.00%
Multiemployer Plans Yellow Zone Funded Status Percentage	0.00%
Employee Benefit Plan [Member]
Defined Contribution Plans [Line Items]
Defined Contribution Plan, Cost Recognized	$ 600	$ 600	$ 700
Profit Sharing and Thrift Employee Benefit Plan [Member]
Defined Contribution Plans [Line Items]
Defined Contribution Plan, Cost Recognized	$ 3,400	$ 4,600	$ 3,400

Segment Information (Details) - USD ($)
$ in Thousands

3 Months Ended

12 Months Ended

Dec. 31, 2017

^[1]

Sep. 30, 2017

Jun. 30, 2017

Mar. 31, 2017

Dec. 31, 2016

^[1]

Sep. 30, 2016

Jun. 30, 2016

Mar. 31, 2016

Dec. 31, 2017

Dec. 31, 2016

Dec. 31, 2015

Contract revenues

$ 373,501

$ 373,502

$ 356,185

$ 300,129

$ 343,660

$ 283,259

$ 261,934

$ 253,634

$ 1,403,317

$ 1,142,487

$ 1,061,681

29,558

38,754

44,841

T&D [Member]

Contract revenues

879,372

818,972

794,898

39,631

63,459

63,155

C&I [Member]

Contract revenues

523,945

323,515

266,783

General Corporate [Member]

25,048

13,920

13,592

$ (35,121)

$ (38,625)

$ (31,906)

[1]	Results for the fourth quarter of 2017 include a net Tax Act benefit of $7.8 million, or $0.48 and $0.47 per basic and diluted share, respectively. See further discussion in Note 10 — Income Taxes to our Financial Statements.

Segment Information (Details 1) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ 603,788	$ 573,495
T&D [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	257,834	235,548
C&I [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	152,207	125,696
General Corporate [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ 193,747	$ 212,251

Segment Information (Details 2) - USD ($) $ in Thousands	12 Months Ended
Segment Information (Details 2) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Depreciation and amortization	$ 38,576	$ 39,122	$ 38,029
T&D [Member]
Segment Reporting Information [Line Items]
Depreciation and amortization	34,990	35,947	35,456
C&I [Member]
Segment Reporting Information [Line Items]
Depreciation and amortization	$ 3,586	$ 3,175	$ 2,573

Segment Information (Details Textual) - USD ($)
$ in Thousands

3 Months Ended

12 Months Ended

Dec. 31, 2017

Sep. 30, 2017

Jun. 30, 2017

Mar. 31, 2017

Dec. 31, 2016

Sep. 30, 2016

Jun. 30, 2016

Mar. 31, 2016

Dec. 31, 2017

Dec. 31, 2016

Dec. 31, 2015

Canadian Operation [Member]

$ 373,501

^[1]

$ 373,502

$ 356,185

$ 300,129

$ 343,660

^[1]

$ 283,259

$ 261,934

$ 253,634

$ 1,403,317

$ 1,142,487

$ 1,061,681

Assets

603,788

573,495

603,788

573,495

Assets

$ 40,000

$ 45,500

40,000

45,500

CANADA

84,100

36,500

1,500

TD [Member] | CANADA

18,700

26,900

1,400

CI [Member] | CANADA