Reconciliation of Ongoing Earnings (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Reconciliation Ongoing Earnings To Net Income Attributable To Controlling Interests [Abstract]
Ongoing Earnings	$ 80	$ 211	$ 223	$ 413
Tax levelization	(5)	(4)	(12)	(6)
CVO mark-to-market	0	4	8	4
Merger and integration costs, net of tax (Note 2)	(13)	(7)	(18)	(21)
CR3 indemnification adjustment (charge), net of tax	5	(26)	5	(26)
Continuing income attributable to noncontrolling interests, net of tax	1	2	3	3
Income from continuing operations	68	180	209	367
Discontinued operations, net of tax	(4)	(2)	7	(4)
Net income attributable to noncontrolling interests, net of tax	(1)	(2)	(3)	(3)
Net income attributable to controlling interests	63	176	213	360
Tax information [Details]
CVO mark-to-market, tax benefit (expense)	0		0
Impairment, tax benefit (expense)	0	0	0	0
Merger and integration costs, tax benefit (expense)	6	4	8	4
CR3 indemnification charge, tax benefit (expense)	(3)	18	(3)	18
Plant retirement charge, tax benefit (expense)	$ 0	$ 0	$ 0	$ 0