Accumulated Other Comprehensive Income (Amounts Reclassified from AOCI) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Accumulated Other Comprehensive Income [Line Items]
Interest Expense - Amortization of Derivative Instruments	$ 12,332	$ 12,603	$ 25,099	$ 25,394
Total	(12,029)	11,619	(25,835)	18,023
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	23	48	47
Interest Expense - Settlement Payments	(550)	97	(1,126)	560
Total	$ (526)	$ 120	$ (1,078)	$ 607