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	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Interest Rate Cash Flow Hedges [Roll Forward]
Balance at beginning of period	$ (7,462)	$ (11,706)	$ (16,624)
Amount of loss recognized in cumulative other comprehensive loss	(1,149)	(776)	(103)
Amount of loss reclassified from cumulative other comprehensive loss into interest expense	4,924	5,020	5,021
Unrealized gain on derivative instruments	3,775	4,244	4,918
Balance at end of period	$ (3,687)	$ (7,462)	$ (11,706)