Changes in Accumulated Other Comprehensive (Loss) Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Changes in accumulated other comprehensive loss by component
Accumulated comprehensive (loss) income at beginning of the year			$ (896,994)	$ 5,671
Other comprehensive (loss) income before reclassifications			(202,200)	(90,308)
Amounts reclassified from accumulated other comprehensive (loss) income			126,170	13,307
Total other comprehensive income (loss)	$ 217,956	$ (24,525)	(76,030)	(77,001)
Ending balance	(973,024)	(71,330)	(973,024)	(71,330)
Changes related to cash flow derivative hedges
Changes in accumulated other comprehensive loss by component
Accumulated comprehensive (loss) income at beginning of the year			(826,026)	43,324
Other comprehensive (loss) income before reclassifications			(183,646)	(84,000)
Amounts reclassified from accumulated other comprehensive (loss) income			125,170	10,447
Total other comprehensive income (loss)			(58,476)	(73,553)
Ending balance	(884,502)	(30,229)	(884,502)	(30,229)
Changes in defined benefit plans
Changes in accumulated other comprehensive loss by component
Accumulated comprehensive (loss) income at beginning of the year			(31,207)	(23,994)
Other comprehensive (loss) income before reclassifications			1,249	(4,948)
Amounts reclassified from accumulated other comprehensive (loss) income			1,000	863
Total other comprehensive income (loss)			2,249	(4,085)
Ending balance	(28,958)	(28,079)	(28,958)	(28,079)
Foreign currency translation adjustments
Changes in accumulated other comprehensive loss by component
Accumulated comprehensive (loss) income at beginning of the year			(39,761)	(13,659)
Other comprehensive (loss) income before reclassifications			(19,803)	(1,360)
Amounts reclassified from accumulated other comprehensive (loss) income			0	1,997
Total other comprehensive income (loss)			(19,803)	637
Ending balance	$ (59,564)	$ (13,022)	$ (59,564)	$ (13,022)