Derivative Instruments - Schedule of Gain or Loss Recognized on Interest Rate Derivatives Designated as Cash Flow Hedges (Details) - Cash flow hedging - Designated as hedging instrument - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized in cumulative other comprehensive loss	$ 67	$ (154)
Amount of loss reclassified from cumulative other comprehensive loss into interest expense	$ 50	$ 1