Changes in Accumulated Other Comprehensive Income (Loss) (Changes by Component)(Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Other comprehensive income (loss) before reclassifications	$ 392,417	$ 73,558	$ (720,570)
Amounts reclassified from accumulated other comprehensive loss	189,802	338,391	289,131
Total other comprehensive income (loss)	582,219	411,949	(431,439)
Accumulated comprehensive loss at end of period	(334,265)	(916,484)
Changes related to cash flow derivative hedges
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(820,850)	(1,232,073)	(826,026)
Other comprehensive income (loss) before reclassifications	381,865	73,973	(697,671)
Amounts reclassified from accumulated other comprehensive loss	188,630	337,250	291,624
Total other comprehensive income (loss)	570,495	411,223	(406,047)
Ending balance	(250,355)	(820,850)	(1,232,073)
Changes in defined benefit plans
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(28,083)	(26,447)	(31,207)
Other comprehensive income (loss) before reclassifications	(6,755)	(2,777)	3,053
Amounts reclassified from accumulated other comprehensive loss	1,172	1,141	1,707
Total other comprehensive income (loss)	(5,583)	(1,636)	4,760
Ending balance	(33,666)	(28,083)	(26,447)
Foreign currency translation adjustments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(67,551)	(69,913)	(39,761)
Other comprehensive income (loss) before reclassifications	17,307	2,362	(25,952)
Amounts reclassified from accumulated other comprehensive loss	0	0	(4,200)
Total other comprehensive income (loss)	17,307	2,362	(30,152)
Ending balance	(50,244)	(67,551)	(69,913)
AOCI including portion attributable to noncontrolling interest
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(916,484)	(1,328,433)	(896,994)
Ending balance	$ (334,265)	$ (916,484)	$ (1,328,433)