Stockholders' Equity and Stock-Based Compensation (Details) (USD $) In Millions, except Share data	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Common shares repurchased:
Total shares repurchased	10,500,000	200,000	12,200,000	600,000
Average purchase price per share	$ 16.28	$ 17.72	$ 16.18	$ 14.51
Common shares issued	1,100,000	200,000	3,400,000	1,400,000
Authority remaining at end of period for repurchases	$ 144.1		$ 144.1
Authority remaining at end of period for share repurchases, terminated plan		38,800,000		38,800,000
Common Stock [Member]
Common shares repurchased:
Open market, shares	9,600,000	0	9,600,000	0
Benefit plans, shares	900,000	200,000	2,600,000	600,000