Subsequent Events (Details) - USD ($) $ in Thousands		12 Months Ended
	Feb. 08, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Jul. 15, 2016
Subsequent Events
Payments of Financing Costs			$ 2,320		$ 2,132
Term loan facility
Subsequent Events
Original issue discount			1,953	$ 1,629
Payments of Financing Costs			2,120
Term loan facility | Senior credit facilities
Subsequent Events
Borrowings under senior credit facility			315,540			$ 130,000
Term loan facility | Senior credit facilities | Subsequent
Subsequent Events
Borrowings under senior credit facility	$ 315,500
Term loan facility | ABR | Senior credit facilities
Subsequent Events
Interest rate margin (as a percent)	3.25%
Term loan facility | Euro dollar | Senior credit facilities
Subsequent Events
Interest rate margin (as a percent)	4.25%
Revolving credit facility
Subsequent Events
Payments of Financing Costs			$ 200
Amended term loan facility | Senior credit facilities | Annual estimate | Subsequent
Subsequent Events
Payments of Financing Costs		$ 923
Amended term loan facility | ABR | Senior credit facilities | Subsequent
Subsequent Events
Interest rate margin (as a percent)	2.50%
Amended term loan facility | Euro dollar | Senior credit facilities | Subsequent
Subsequent Events
Interest rate margin (as a percent)	3.50%
First option | Term loan facility | Senior credit facilities | Subsequent
Subsequent Events
Interest rate margin (as a percent)	0.50%
First option | Term loan facility | Senior credit facilities | Minimum
Subsequent Events
Additional fixed interest rate spread (as a percent)				1.00%
Additional interest margin added to fixed and variable rates (as a percent)				1.00%
First option | Term loan facility | Base rate | Senior credit facilities
Subsequent Events
Fixed interest rate base (as a percent)	2.50%
First option | Term loan facility | Federal funds | Senior credit facilities
Subsequent Events
Interest rate margin (as a percent)				0.50%
Variable rate basis description			Federal funds
First option | Term loan facility | Federal funds | Senior credit facilities | Subsequent
Subsequent Events
Variable rate basis description	Federal funds
First option | Term loan facility | Fixed rate | Senior credit facilities
Subsequent Events
Fixed interest rate base (as a percent)				2.50%
First option | Term loan facility | Prime | Senior credit facilities
Subsequent Events
Variable rate basis description			Prime Rate
First option | Term loan facility | Prime | Senior credit facilities | Subsequent
Subsequent Events
Variable rate basis description	Prime Rate
First option | Term loan facility | One month London Interbank Offered Rate | Senior credit facilities
Subsequent Events
Variable rate basis description			LIBOR for a one month interest period
First option | Term loan facility | One month London Interbank Offered Rate | Senior credit facilities | Subsequent
Subsequent Events
Variable rate basis description	LIBOR for a one month interest period
Second option | Term loan facility | Senior credit facilities | Minimum | Subsequent
Subsequent Events
Additional fixed interest rate spread (as a percent)	2.00%
Additional interest margin added to fixed and variable rates (as a percent)	1.00%
Second option | Term loan facility | Base rate | Senior credit facilities | Subsequent
Subsequent Events
Fixed interest rate base (as a percent)	3.50%
Second option | Term loan facility | Fixed rate | Senior credit facilities
Subsequent Events
Fixed interest rate base (as a percent)				3.50%
Additional fixed interest rate spread (as a percent)				1.00%
Second option | Revolving credit facility | Federal funds | Senior credit facilities
Subsequent Events
Variable rate basis description			federal funds
Second option | Revolving credit facility | Fixed rate | Maximum | Subsequent
Subsequent Events
Fixed interest rate base (as a percent)	1.00%
Second option | Revolving credit facility | Prime | Senior credit facilities
Subsequent Events
Variable rate basis description			Prime Rate
Second option | Revolving credit facility | One month London Interbank Offered Rate | Senior credit facilities
Subsequent Events
Variable rate basis description			LIBOR for a one month interest period