Accumulated Other Comprehensive Loss (Amounts Reclassified from AOCI) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Mark-to-Market and Settlement Loss on Interest Rate Protection Agreements	$ 0	$ (11,546)	$ 0
Interest Expense - Amortization of IRPAs	59,430	67,424	72,178
Total	5,553	(33,223)	(76,014)
Interest Rate Swap | Reclassification out of Accumulated Other Comprehensive Loss | Interest Rate Protection Agreements
Accumulated Other Comprehensive Income (Loss) [Line Items]
Mark-to-Market and Settlement Loss on Interest Rate Protection Agreements	0	12,990	0
Interest Expense - Amortization of IRPAs	390	524	1,358
Interest Expense - Settlement Payments	7,123	5,529	3,991
Total	$ 7,513	$ 19,043	$ 5,349