Changes in Accumulated Other Comprehensive Income (Loss) (Changes by Component) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Other comprehensive (loss) income before reclassifications	$ (306,089)	$ 392,417	$ 73,558
Amounts reclassified from accumulated other comprehensive loss	12,620	189,802	338,391
Total other comprehensive (loss) income	(293,469)	582,219	411,949
Changes related to cash flow derivative hedges
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(250,355)	(820,850)	(1,232,073)
Other comprehensive (loss) income before reclassifications	(297,994)	381,865	73,973
Amounts reclassified from accumulated other comprehensive loss	11,133	188,630	337,250
Total other comprehensive (loss) income	(286,861)	570,495	411,223
Ending balance	(537,216)	(250,355)	(820,850)
Changes in defined benefit plans
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(33,666)	(28,083)	(26,447)
Other comprehensive (loss) income before reclassifications	6,156	(6,755)	(2,777)
Amounts reclassified from accumulated other comprehensive loss	1,487	1,172	1,141
Total other comprehensive (loss) income	7,643	(5,583)	(1,636)
Ending balance	(26,023)	(33,666)	(28,083)
Foreign currency translation adjustments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(50,244)	(67,551)	(69,913)
Other comprehensive (loss) income before reclassifications	(14,251)	17,307	2,362
Amounts reclassified from accumulated other comprehensive loss	0	0	0
Total other comprehensive (loss) income	(14,251)	17,307	2,362
Ending balance	(64,495)	(50,244)	(67,551)
Accumulated other comprehensive (loss) income
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(334,265)	(916,484)	(1,328,433)
Ending balance	$ (627,734)	$ (334,265)	$ (916,484)