Derivatives - Additional Information (Details) $ in Thousands	1 Months Ended	3 Months Ended	12 Months Ended
	Aug. 31, 2014 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jan. 31, 2014 USD ($)
Derivative [Line Items]
Mark-to-Market Loss on Interest Rate Protection Agreements			$ 1,896	$ 0	$ (11,546)
2014 Swaps
Derivative [Line Items]
Debt instrument, LIBOR Rate			one month LIBOR
Swaps, Number of Instruments Held							4
Swaps, Notional Amount							$ 200,000
Swaps, Average Fixed Interest Rate							2.29%
2015 Swaps
Derivative [Line Items]
Debt instrument, LIBOR Rate			one month LIBOR
Swaps, Number of Instruments Held						6
Swaps, Notional Amount						$ 260,000
Swaps, Average Fixed Interest Rate						1.79%
Settled Swaps
Derivative [Line Items]
Debt instrument, LIBOR Rate	three month LIBOR
Swaps, Number of Instruments Held	3
Swaps, Notional Amount	$ 220,000
Mark-to-Market Loss on Interest Rate Protection Agreements		$ 12,990
Settled Swaps, Cost of Hedge					$ 11,546
Treasury Lock
Derivative [Line Items]
Debt instrument, LIBOR Rate			ten year U.S. Treasury
Swaps, Number of Instruments Held			2
Swaps, Notional Amount			$ 100
Swaps, Average Fixed Interest Rate			2.18%
Mark-to-Market Loss on Interest Rate Protection Agreements			$ 1,896