Earnings Per Share (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Earnings Per Share [Abstract]
Income from Continuing Operations Used for Diluted Earnings Per Share Calculation	$ 965	$ 412	$ 631
Weighted Average Number of Shares Outstanding, Basic (in shares)	178	176	175
Incremental Shares From Assumed Conversion of Dilutive Stock Options and Restricted Stock (in shares)	2	3	2
Weighted Average Number of Shares Outstanding, Diluted (in shares)	180	179	177
Earnings from Continuing Operations Per Share, Basic (in dollars per share)	$ 5.43	$ 2.34	$ 3.61
Earnings from Continuing Operations Per Share, Diluted (in dollars per share)	$ 5.37	$ 2.31	$ 3.56
Earnings Per Share Additional Information [Abstract]
Number of antidilutive stock options, shares of restricted stock and shares of common stock in rabbi trust excluded from calculation above (in shares)	3	3	2
Weighted average option exercise price per share (in dollars per share)	$ 97.46	$ 85.40	$ 74.01