Equity, Stock Repurchase Activities (Details) (USD $)	12 Months Ended		1 Months Ended	12 Months Ended	1 Months Ended	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Feb. 28, 2010 Stock Repurchase Program 2010 [Member]	Dec. 31, 2011 Stock Repurchase Program 2010 [Member]	Mar. 31, 2008 Stock Repurchase Program 2008 [Member]	Dec. 31, 2011 Stock Repurchase Program 2008 [Member]
Common stock authorized for repurchase under the 2010 and 2008 Stock Repurchase Programs			$ 1,000,000,000		$ 1,000,000,000
Stock Repurchased and Retired During Period, Shares	17,500,000	19,700,000
Common Stock Repurchased Under Stock Repurchase Program Average Purchase Price	$ 30.93	$ 28.67
Common stock repurchased and retired under stock repurchase programs, value	541,200,000	563,500,000
Stock Repurchase Program, Remaining Authorized Repurchase Amount				213,800,000		0
Repurchase of Common Stock from Employees for Net Issuance of Shares	200,000	100,000
Common Stock Average Purchase Price	$ 35.98	$ 25.75
Shares Repuchased And Retired Related To Net Issuances	$ 7,400,000	$ 1,900,000