Fair Value Measurements and Derivative Instruments (Details 9) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 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
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	11,919	48,996
Amount of Gain (Loss) Recognized in Income on Hedged Item	44,157	102
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	13,682	18,278
Amount of Gain (Loss) Recognized in Income on Hedged Item	32,389	31,045
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	(1,763)	7,817
Amount of Gain (Loss) Recognized in Income on Hedged Item	2,070	(7,223)
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)