Fair Value Measurements (Details) - Interest Rate Swap [Member] - Fair Value, Inputs, Level 2 [Member] - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Fair Value Assets and Liabilities Measured on Recurring Basis Fair value and input reconciliation [Roll Forward]
Cash Flow Hedge Fair Value, Beginning Balance	$ (3,175)	$ (4,938)
Unrealized losses included in interest expense	(23)	(22)
Losses on interest rate swaps reclassified into interest expense from accumulated other comprehensive loss	755	818
Unrealized losses included in equity and partners’ capital	(355)	(1,085)
Cash Flow Hedge Fair Value, Ending Balance	$ (2,798)	$ (5,227)