Long-Term Debt and Credit Facility (Details)			6 Months Ended
	Mar. 31, 2015 USD ($)	Jul. 01, 2013 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)	Jul. 31, 2013 USD ($)
Debt Instrument [Line Items]
Amount retired under prior credit facility		$ 232,300,000
Amount of cash on hand to fund transactions		7,000,000
Actual financial leverage ratio			2.96
Proceeds from line of credit			$ 26,000,000	$ 0
Other Long-term Debt			11,800,000		$ 12,400,000
Other Loans Payable			100,000		100,000
Letters of credit issued and outstanding			27,000,000
Long-term debt, fair value			$ 363,200,000		377,000,000
Initial maximum financial leverage ratio			3.25
Remaining borrowing capacity			$ 35,100,000
Minimum permitted fixed charge coverage ratio			1.25
Actual fixed charge coverage ratio			1.31
Insurance Carriers Collateral [Member]
Debt Instrument [Line Items]
Letters of credit issued and outstanding			$ 10,200,000
Work Performance Obligations [Member]
Debt Instrument [Line Items]
Letters of credit issued and outstanding			$ 16,800,000
2013 Interest Rate Swap [Member]
Debt Instrument [Line Items]
Notional Amount						$ 175,000,000
Fixed interest rate						0.87%
Annualized borrowing rate			2.23%
Brinderson LP [Member]
Debt Instrument [Line Items]
Total consideration recorded		147,600,000
2013 Credit Facility [Member]
Debt Instrument [Line Items]
Face amount of debt						$ 650,000,000
Maximum borrowing capacity						300,000,000
Term of credit facility			5 years
Secured Debt			$ 279,800,000		319,400,000	350,000,000
Term of debt instrument			5 years
Amount drawn on credit facility		$ 35,500,000	$ 71,500,000		$ 45,500,000
Annual mandatory prepayment, percent of Excess Cash Flow			50.00%
Minimum Consolidated Leverage Ratio required			2.50
Actual financial leverage ratio					2.90
Term loan repayment	$ 26,500,000
Proceeds from line of credit	$ 26,000,000
Derivative, Amount of Hedged Item						$ 175,000,000
2013 Credit Facility [Member] | LIBOR [Member]
Debt Instrument [Line Items]
Interest rate at period end			2.14%
2013 Credit Facility [Member] | LIBOR [Member] | Minimum [Member]
Debt Instrument [Line Items]
Basis spread on variable rate			1.25%
2013 Credit Facility [Member] | LIBOR [Member] | Maximum [Member]
Debt Instrument [Line Items]
Basis spread on variable rate			2.25%