Credit Facility (Details) - USD ($)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015	Apr. 14, 2014
Line of Credit Facility [Line Items]
Maximum capacity on credit facility				$ 705,000,000
Additional borrowing capacity under certain circumstances				1,000,000,000
Credit facility	$ 485,000,000		$ 485,000,000
Term Loan
Line of Credit Facility [Line Items]
Maximum capacity on credit facility				305,000,000
Credit facility	305,000,000		305,000,000
Revolving Loan
Line of Credit Facility [Line Items]
Maximum capacity on credit facility				$ 400,000,000
Credit facility	$ 180,000,000		$ 180,000,000
Credit Facility
Line of Credit Facility [Line Items]
Effective interest rate	2.57%		2.39%
Remaining borrowing capacity	$ 58,700,000
Credit Facility | LIBOR
Line of Credit Facility [Line Items]
Unused capacity commitment fee percentage threshold	50.00%
Credit Facility | Line of Credit Facility, Interest Rate, Option One | Minimum | LIBOR
Line of Credit Facility [Line Items]
Spread on variable rate basis	1.50%
Credit Facility | Line of Credit Facility, Interest Rate, Option One | Maximum | LIBOR
Line of Credit Facility [Line Items]
Spread on variable rate basis	2.25%
Credit Facility | Line of Credit Facility, Interest Rate, Option Two | Minimum | Base Rate
Line of Credit Facility [Line Items]
Spread on variable rate basis	0.50%
Credit Facility | Line of Credit Facility, Interest Rate, Option Two | Maximum | Base Rate
Line of Credit Facility [Line Items]
Spread on variable rate basis	1.25%
Credit Facility | Line of Credit Facility, Base Rate, Option Two | Federal Funds Effective Rate
Line of Credit Facility [Line Items]
Spread on variable rate basis	0.50%
Credit Facility | Line of Credit Facility, Base Rate, Option Three | One-Month LIBOR
Line of Credit Facility [Line Items]
Spread on variable rate basis	1.00%
Credit Facility | Below Threshold | LIBOR
Line of Credit Facility [Line Items]
Unused capacity fee percentage	0.15%
Credit Facility | Above Threshold | LIBOR
Line of Credit Facility [Line Items]
Unused capacity fee percentage	0.25%
Interest Expense
Line of Credit Facility [Line Items]
Error correction, amount		$ 300,000
Net Loss
Line of Credit Facility [Line Items]
Error correction, amount		$ 300,000