Derivatives - Additional Information (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2018 USD ($)
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%