Earnings Per Share (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Earnings Per Share, Basic and Diluted [Abstract]
Shareholders' net income	$ 57	$ 371
Shares (in thousands):
Weighted average	283,804,000	285,159,000
Common stock equivalents	5,454,000	3,840,000
Total shares	289,258,000	288,999,000
Shareholders' net income per share basic	$ 0.20	$ 1.30
Shareholders net income per share effect of dilution	$ 0	$ (0.02)
Shareholders' net income per share diluted	$ 0.20	$ 1.28
Earnings Per Share, Basic and Diluted, Other Disclosures [Abstract]
Antidilutive options	0	3,800,000
Common shares held in Treasury	80,302,892	77,847,260