Accumulated Other Comprehensive Income (Amounts Reclassified from AOCI) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Settlement Gain on Derivative Instruments	$ 0	$ 1,896	$ 0
Interest Expense - Amortization of IRPAs	50,775	57,199	59,430
Total	27,382	71,029	5,553
Interest Rate Swap | Reclassification out of Accumulated Other Comprehensive Loss | Derivative Instruments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Interest Expense - Amortization of IRPAs	96	205	390
Interest Expense - Settlement Payments	109	4,336	7,123
Total	$ 205	$ 4,541	$ 7,513