Long-Term Debt and Credit Facility - Additional Information (Details)	1 Months Ended	9 Months Ended
	Oct. 31, 2015	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Mar. 31, 2017	Dec. 31, 2015 USD ($)	Oct. 30, 2015 USD ($)
Debt Instrument [Line Items]
Amount retired under prior credit facility						$ 344,700,000
Proceeds from line of credit		$ 42,000,000	$ 26,000,000
Debt designated as third-party debt		9,600,000			$ 9,600,000
Third-party notes and bank debt held		300,000			100,000
Unamortized loan costs		(3,628,000)			(4,294,000)
Long-term debt, fair value		$ 373,400,000			$ 349,100,000
2015 Interest Rate Swap
Debt Instrument [Line Items]
Notional Amount						$ 262,500,000
Fixed interest rate						1.46%
2015 Credit Facility
Debt Instrument [Line Items]
Senior secured credit facility						$ 650,000,000
Maximum borrowing capacity						350,000,000
Term of revolving line of credit	5 years
Term of term loan facility	5 years
Interest rate at period end		2.85%
Term note, due October 30, 2020, annualized rates of 2.85% and 2.47%, respectively		$ 332,500,000
Proceeds from line of credit		36,000,000
Letters of credit issued and outstanding		$ 36,300,000
Portion of amortization of term loan						262,500,000
Initial maximum financial leverage ratio					3.75
Actual financial leverage ratio		3.65
Remaining borrowing capacity		$ 37,400,000
Minimum permitted fixed charge coverage ratio		1.25
Actual fixed charge coverage ratio		1.49
2015 Credit Facility | Insurance Carriers Collateral
Debt Instrument [Line Items]
Letters of credit issued and outstanding		$ 19,400,000
2015 Credit Facility | Work Performance Obligations
Debt Instrument [Line Items]
Letters of credit issued and outstanding		$ 16,800,000
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
2015 Credit Facility | Small Acquisition
Debt Instrument [Line Items]
Proceeds from line of credit		$ 3,000,000
2013 Credit Facility
Debt Instrument [Line Items]
Term note, due October 30, 2020, annualized rates of 2.85% and 2.47%, respectively					$ 345,600,000
Line of credit					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
Line of Credit | 2015 Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity						$ 300,000,000
Proceeds from line of credit		$ 3,000,000