Changes in Accumulated Other Comprehensive (Loss) Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Changes in accumulated other comprehensive loss by component
Accumulated comprehensive loss at beginning of the year			$ (1,328,433)	$ (896,994)
Other comprehensive (loss) income before reclassifications			(14,248)	(503,727)
Amounts reclassified from accumulated other comprehensive loss			265,147	204,332
Total other comprehensive income (loss)	$ 94,528	$ (223,365)	250,899	(299,395)
Ending balance	(1,077,534)	(1,196,389)	(1,077,534)	(1,196,389)
Changes related to cash flow derivative hedges
Changes in accumulated other comprehensive loss by component
Accumulated comprehensive loss at beginning of the year			(1,232,073)	(826,026)
Other comprehensive (loss) income before reclassifications			(9,150)	(483,946)
Amounts reclassified from accumulated other comprehensive loss			263,774	202,978
Total other comprehensive income (loss)			254,624	(280,968)
Ending balance	(977,449)	(1,106,994)	(977,449)	(1,106,994)
Changes in defined benefit plans
Changes in accumulated other comprehensive loss by component
Accumulated comprehensive loss at beginning of the year			(26,447)	(31,207)
Other comprehensive (loss) income before reclassifications			(13,521)	4,213
Amounts reclassified from accumulated other comprehensive loss			1,373	1,354
Total other comprehensive income (loss)			(12,148)	5,567
Ending balance	(38,595)	(25,640)	(38,595)	(25,640)
Foreign currency translation adjustments
Changes in accumulated other comprehensive loss by component
Accumulated comprehensive loss at beginning of the year			(69,913)	(39,761)
Other comprehensive (loss) income before reclassifications			8,423	(23,994)
Amounts reclassified from accumulated other comprehensive loss			0	0
Total other comprehensive income (loss)			8,423	(23,994)
Ending balance	$ (61,490)	$ (63,755)	$ (61,490)	$ (63,755)