Accumulated Other Comprehensive Income (Amounts Reclassified from AOCI) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Accumulated Other Comprehensive Income [Line Items]
Interest Expense - Amortization of Derivative Instruments	$ 12,767	$ 12,791
Total	(13,806)	6,404
Interest Rate Swap | Reclassification out of Accumulated Other Comprehensive Income | Derivative Instruments
Accumulated Other Comprehensive Income [Line Items]
Interest Expense - Amortization of Derivative Instruments	24	24
Interest Expense - Settlement Payments	(576)	463
Total	$ (552)	$ 487