Earnings Per Share (Narrative) (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended		1 Months Ended	0 Months Ended		12 Months Ended
	Dec. 31, 2010	Dec. 31, 2009	Nov. 17, 2011 Accelerated Share Repurchase Program [Member]	May 10, 2011 Accelerated Share Repurchase Program [Member]	May 10, 2011 Accelerated Share Repurchase Program [Member]	Dec. 31, 2011 Accelerated Share Repurchase Program [Member]	Dec. 31, 2011 Share Repurchase Program [Member]	Dec. 31, 2011 Two Thousand And Eight Share Repurchase Program [Member]
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program, authorized amount						$ 500	$ 1,000
Stock repurchase program, shares authorized								10,000,000
Treasury stock, shares acquired	0	0	9,300,000	19,900,000		29,200,000
Cash payment for share repurchase under ASR program						500.0
Percentage of shares held by investment bank due to holdback agreement				20.00%
Value of shares held by investment bank pending settlement of accelerated share repurchase					$ 100
Weighted average price of common stock						$ 17.13