Subsequent Events (Details) (USD $)	12 Months Ended		0 Months Ended	3 Months Ended	7 Months Ended	12 Months Ended	41 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Feb. 20, 2015	Mar. 31, 2015	Sep. 30, 2015	Sep. 30, 2016	Feb. 20, 2020	Feb. 19, 2015
Subsequent Event [Line Items]
Debt Instrument, Unamortized Discount	$ 2,300,000
Debt Issuance Cost	2,635,000	3,890,000
Senior Credit Facility, net of discount
Subsequent Event [Line Items]
Maximum borrowing capacity	450,000,000
Period of total debt to EBITDA ratio	12 months
Debt Instrument, Unamortized Discount	2,300,000
Senior Credit Facility, net of discount | Subsequent Events
Subsequent Event [Line Items]
Maximum borrowing capacity			400,000,000
Revolving credit facility
Subsequent Event [Line Items]
Maximum borrowing capacity	200,000,000
Amount drawn	72,800,000
Revolving credit facility | Subsequent Events
Subsequent Event [Line Items]
Maximum borrowing capacity			200,000,000
Aggregate additional principal amount that may be borrowed			100,000,000
Outstanding borrowing			147,299,000
Letter of credit facility
Subsequent Event [Line Items]
Maximum borrowing capacity	100,000,000
Letter of credit facility | Subsequent Events
Subsequent Event [Line Items]
Maximum borrowing capacity			100,000,000
Outstanding borrowing			53,449,000
Swing-line loans | Subsequent Events
Subsequent Event [Line Items]
Maximum borrowing capacity			20,000,000
Term loan facility
Subsequent Event [Line Items]
Maximum borrowing capacity	250,000,000
Term loan facility | Subsequent Events
Subsequent Event [Line Items]
Maximum borrowing capacity			200,000,000					250,000,000
Amount drawn			10,400,000
Year one amortization of principal			15,000,000
Year two amortization of principal			15,000,000
Year three amortization of principal			20,000,000
Year four amortization of principal			20,000,000
Year five amortization of principal			20,000,000
Year six amortization of principal			110,000,000
Forecast | Subsequent Events
Subsequent Event [Line Items]
Losses on the extinguishment of debt related to debt discount and debt issuance costs				$ 650,000
Maximum | Senior Credit Facility, net of discount
Subsequent Event [Line Items]
Total debt to EBITDA ratio that is required to be maintained	4.5
Maximum | Forecast | Senior Credit Facility, net of discount | Subsequent Events
Subsequent Event [Line Items]
Total debt to EBITDA ratio that is required to be maintained					4.0	3.75	3.5
Minimum | Senior Credit Facility, net of discount
Subsequent Event [Line Items]
Fixed charge coverage ratio that is required to be maintained	1.25
Minimum | Senior Credit Facility, net of discount | Subsequent Events
Subsequent Event [Line Items]
Fixed charge coverage ratio that is required to be maintained			1.25
LIBOR Loans | Senior Credit Facility, net of discount | Subsequent Events
Subsequent Event [Line Items]
Period of total debt to EBITDA ratio			12 months
Variable rate basis			LIBOR
LIBOR Loans | LIBOR | Senior Credit Facility, net of discount
Subsequent Event [Line Items]
Variable rate basis	LIBOR
Base rate loans | Base Rate | Senior Credit Facility, net of discount
Subsequent Event [Line Items]
Variable rate basis	federal funds rate
Interest rate margin on variable rate basis (as a percent)	0.50%
Base rate loans | Base Rate | Senior Credit Facility, net of discount | Subsequent Events
Subsequent Event [Line Items]
Variable rate basis			federal funds rate
Interest rate margin on variable rate basis (as a percent)			0.50%
Base rate loans | Prime Rate | Senior Credit Facility, net of discount
Subsequent Event [Line Items]
Variable rate basis	Bank of America prime rate
Base rate loans | Prime Rate | Senior Credit Facility, net of discount | Subsequent Events
Subsequent Event [Line Items]
Variable rate basis			Bank of America prime rate
Base rate loans | LIBOR | Senior Credit Facility, net of discount
Subsequent Event [Line Items]
Variable rate basis	LIBOR
Interest rate margin on variable rate basis (as a percent)	1.00%
Base rate loans | LIBOR | Senior Credit Facility, net of discount | Subsequent Events
Subsequent Event [Line Items]
Variable rate basis			LIBOR
Interest rate margin on variable rate basis (as a percent)			1.00%