Accumulated Other Comprehensive Income (Amounts Reclassified from AOCI) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Accumulated Other Comprehensive Income [Line Items]
Interest Expense - Amortization of Derivative Instruments	$ 12,466	$ 12,424	$ 37,565	$ 37,818
Total	39,218	(5,139)	13,383	12,884
Interest Rate Swap | Reclassification out of Accumulated Other Comprehensive Income | Derivative Instruments
Accumulated Other Comprehensive Income [Line Items]
Interest Expense - Amortization of Derivative Instruments	83	24	131	71
Interest Expense - Settlement Payments	(287)	(102)	(1,413)	458
Total	$ (204)	$ (78)	$ (1,282)	$ 529