Long-Term Debt and Credit Facility - Narrative (Details)		12 Months Ended
	Oct. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Mar. 31, 2017	Jul. 31, 2013 USD ($)
Debt Instrument [Line Items]
Credit Facility, Retired Amount	$ 344,700,000
Debt issuance costs		$ 3,377,000	$ 157,000	$ 1,964,000
Interest Expense		16,044,000	12,943,000	$ 13,169,000
Other Long-term Debt		9,600,000	12,400,000
Other Loans Payable		100,000	100,000
Long-term Debt, Fair Value		349,100,000	377,000,000
BPPC
Debt Instrument [Line Items]
Other Long-term Debt		$ 1,900,000
2015 Interest Rate Swap
Debt Instrument [Line Items]
Derivative, Fixed Interest Rate	1.46%
Derivative Asset, Notional Amount	$ 262,500,000
Derivative, Variable Interest Rate		2.93%
2015 Credit Facility
Debt Instrument [Line Items]
Debt Instrument, Face Amount	650,000,000
Line of Credit Facility, Maximum Borrowing Capacity	$ 300,000,000	$ 350,000,000
Line of Credit Facility, Expiration Period	5 years
Secured Debt		345,625,000	0
Debt Instrument, Term	5 years
Business Combination, Consideration Paid	$ 4,400,000
Debt issuance costs		1,800,000
Third party arranging fees	2,600,000
Unamortized loan costs	3,500,000
Interest Expense		800,000
Letters of Credit Outstanding, Amount		$ 36,700,000
Derivative, Amount of Hedged Item	$ 262,500,000
Credit Facility Maximum Consolidated Leverage Ratio		3.75
Credit Facility Actual Consolidated Leverage Ratio		2.87
Line of Credit Facility, Remaining Borrowing Capacity		$ 110,300,000
Credit Facility Minimum Consolidated Fixed Charge Ratio		1.25
Credit Facility Actual Consolidated Fixed Charge Ratio		1.70
2015 Credit Facility | Scenario, Forecast
Debt Instrument [Line Items]
Credit Facility Maximum Consolidated Leverage Ratio					3.5
2015 Credit Facility | Insurance Carriers Collateral
Debt Instrument [Line Items]
Letters of Credit Outstanding, Amount		$ 16,600,000
2015 Credit Facility | Work Performance Obligations
Debt Instrument [Line Items]
Letters of Credit Outstanding, Amount		$ 20,100,000
2015 Credit Facility | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Debt Instrument, Interest Rate at Period End		3.03%
2015 Credit Facility | London Interbank Offered Rate (LIBOR) | Minimum
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate		1.25%
2015 Credit Facility | London Interbank Offered Rate (LIBOR) | Maximum
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate		2.25%
2013 Credit Facility
Debt Instrument [Line Items]
Debt Instrument, Face Amount						$ 650,000,000
Secured Debt		$ 0	319,375,000
Line of Credit Facility, Amount Outstanding		$ 0	$ 45,500,000