Fair Value Measurements and Derivative Instruments (Details 8) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Interest rate swaps | Extinguishment of unsecured senior notes
Effect of derivative instruments involved in fair value hedging on the consolidated financial statements
Adjustment To Deferred Carrying Amount Of Previously Hedged Instrument	$ 9,698		$ 9,698
Fair Value Hedging
Effect of derivative instruments involved in fair value hedging on the consolidated financial statements
Amount of Gain (Loss) Recognized in Income on Derivative	754	15,172	12,032	48,328
Amount of Gain (Loss) Recognized in Income on Hedged Item	21,195	(2,719)	33,660	(11,888)
Fair Value Hedging | Interest rate swaps | Interest expense, net of interest capitalized
Effect of derivative instruments involved in fair value hedging on the consolidated financial statements
Amount of Gain (Loss) Recognized in Income on Derivative	3,054	4,484	12,916	13,365
Amount of Gain (Loss) Recognized in Income on Hedged Item	8,634	7,910	23,001	23,504
Fair Value Hedging | Interest rate swaps | Other income (expense)
Effect of derivative instruments involved in fair value hedging on the consolidated financial statements
Amount of Gain (Loss) Recognized in Income on Derivative	(2,300)	10,688	(884)	12,062
Amount of Gain (Loss) Recognized in Income on Hedged Item	2,863	(10,629)	961	(11,672)
Fair Value Hedging | Foreign currency forward contracts | Other income (expense)
Effect of derivative instruments involved in fair value hedging on the consolidated financial statements
Amount of Gain (Loss) Recognized in Income on Derivative				22,901
Amount of Gain (Loss) Recognized in Income on Hedged Item				$ (23,720)