Stockholder's Equity (Details) (USD $)	1 Months Ended	2 Months Ended		12 Months Ended
	Feb. 13, 2013	Feb. 16, 2012	Feb. 17, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Common Stock Activity [Abstract]
Shares of Common Stock Sold				13,570,000
Public Offering Price of Common Stock Sold				$ 105.50
Common Stock, Par (in dollars per share)				$ 0.01	$ 0.01
Proceeds From Issuance Or Sale Of Equity				$ 1,388,000,000
An aggregate maximum of shares of common stock authorized for repurchase				10,000,000
Remaining shares available for purchase under share repurchase authorization				6,386,200
Dividends Common Stock Cash	$ 0.1875	$ 0.17	$ 0.16
Common Stock Issued Under Equity Compensation Plans				2,471,000	1,395,000	1,482,000
Treasury Stock Purchased				(575,000)	(267,000)	(115,000)
Common Stock Issued Under Employee Stock Purchase Plan				164,000	135,000	114,000
Treasury Stock Issued Under Other Equity Compensation Plans				553,000	109,000	87,000
Common Stock Sold					13,570,000
Common Shares Issued				271,958,495	269,323,084	254,223,000	252,627,000
Treasury Shares Outstanding				(326,264)	(303,633)	(146,000)	(118,000)
Common Shares Outstanding				271,632,000	269,019,000	254,077,000	252,509,000
Series E Junior Participating Preferred Stock (Series E) Authorized				1,500,000
Series E Junior Participating Preferred Stock (Series E) Authorized, total, following two-for-one stock split				3,000,000