Long-Term Debt and Credit Facility - Additional Information (Details)		1 Months Ended	3 Months Ended
	Oct. 30, 2015 USD ($)	Mar. 31, 2016 USD ($)	Mar. 31, 2016 USD ($)	Mar. 31, 2015 USD ($)	Mar. 31, 2017	Dec. 31, 2015 USD ($)
Debt Instrument [Line Items]
Amount retired under prior credit facility	$ 344,700,000
Proceeds from line of credit			$ 34,000,000	$ 26,000,000
Debt designated as third-party debt		$ 9,600,000	9,600,000			$ 9,600,000
Third-party notes and bank debt held		200,000	200,000			100,000
Unamortized loan costs		(4,072,000)	(4,072,000)			(4,294,000)
Long-term debt, fair value		$ 388,700,000	$ 388,700,000			$ 349,100,000
2015 Interest Rate Swap
Debt Instrument [Line Items]
Notional Amount	$ 262,500,000
Fixed interest rate	1.46%
Annualized borrowing rate		3.46%	3.46%
2015 Credit Facility
Debt Instrument [Line Items]
Senior secured credit facility	$ 650,000,000
Maximum borrowing capacity	$ 300,000,000	$ 350,000,000	$ 350,000,000
Term of revolving line of credit	5 years
Term of term loan facility			5 years
Term note, due October 30, 2020, annualized rates of 2.63% and 2.61%, respectively		341,300,000	$ 341,300,000
Proceeds from line of credit		4,000,000	34,000,000
Letters of credit issued and outstanding		$ 31,800,000	$ 31,800,000
Actual financial leverage ratio		3.42	3.42
Portion of amortization of term loan	$ 262,500,000
Initial maximum financial leverage ratio						3.75
Remaining borrowing capacity		$ 65,900,000	$ 65,900,000
Minimum permitted fixed charge coverage ratio		1.25	1.25
Actual fixed charge coverage ratio		1.57	1.57
2015 Credit Facility | Insurance Carriers Collateral
Debt Instrument [Line Items]
Letters of credit issued and outstanding		$ 16,600,000	$ 16,600,000
2015 Credit Facility | Work Performance Obligations
Debt Instrument [Line Items]
Letters of credit issued and outstanding		$ 15,200,000	$ 15,200,000
2015 Credit Facility | LIBOR
Debt Instrument [Line Items]
Interest rate at period end		2.48%	2.48%
2015 Credit Facility | LIBOR | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate			1.25%
2015 Credit Facility | LIBOR | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate			2.25%
2015 Credit Facility | Underground Solutions
Debt Instrument [Line Items]
Proceeds from line of credit			$ 30,000,000
Initial maximum financial leverage ratio		4.00	4.00
2013 Credit Facility
Debt Instrument [Line Items]
Term note, due October 30, 2020, annualized rates of 2.63% and 2.61%, respectively						$ 345,600,000
Line of credit, 2.44%						0
Held-for-sale
Debt Instrument [Line Items]
Debt listed as held for sale						$ 1,924,000
Scenario, Forecast | 2015 Credit Facility
Debt Instrument [Line Items]
Initial maximum financial leverage ratio					3.75