Fair Value Measurements and Derivative Instruments (Income Statement Hedging Instruments) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Interest rate swaps | Extinguishment of unsecured senior notes
Effect of derivative instruments involved in fair value hedging on the consolidated financial statements
Amount of Gain (Loss) Recognized in Income on Derivative	$ 0	$ 0
Adjustment To Deferred Carrying Amount Of Previously Hedged Instrument	0	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	(62,276)	11,919
Amount of Gain (Loss) Recognized in Income on Hedged Item	106,488	44,157
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	9,354	13,682
Amount of Gain (Loss) Recognized in Income on Hedged Item	37,745	32,389
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	(71,630)	(1,763)
Amount of Gain (Loss) Recognized in Income on Hedged Item	$ 68,743	$ 2,070