Equity - Common Stock (Details) (USD $) In Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Dec. 31, 2010
Common Stock [Details]
Common shares, authorized	500		500		500
Common shares, outstanding	295		295		293
Total issuances - shares	0.3	0.3	1.7	11.8
Issuance through 401(k) and or IPP - shares	0	0.3	0	11.0
Total issuances - net proceeds	$ 16	$ 14	$ 42	$ 419
Issuances through 401(k) and or IPP - net proceeds	$ 0	$ 13	$ 1	$ 418