Income Taxes - Continuing Operations (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended			1 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012 Minimum [Member] State and Local Jurisdiction [Member]	Dec. 31, 2012 Maximum [Member] State and Local Jurisdiction [Member]
Income taxes related to adjustments included in common shareholder’s equity:
Provision (benefit) for income taxes related to continuing operations	$ (51)	$ 91	$ 133	$ 152	$ (81)	$ (98)	$ (939)	$ (288)	$ 325	$ (1,406)	$ (1,431)
Unrealized gains (losses) on securities available-for-sale, not other-than-temporarily impaired, net									(62)	7	13
Unrealized gains on other-than-temporarily impaired debt securities available-for-sale									(1)	1	3
Unrealized gains on cash flow hedging instruments									143	75	52
Changes in funded status of postretirement benefit plans									8	(8)	(6)
Foreign currency translation adjustments									(10)	1	(1)
Total									403	(1,330)	(1,370)
Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current benefit									(917)	(958)	(772)
Deferred income tax (benefit) provision									1,242	(448)	(659)
Total income provision (benefit)	(51)	91	133	152	(81)	(98)	(939)	(288)	325	(1,406)	(1,431)
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Deferred income tax provision (benefit) (excluding the effects of other components)									1,443	(597)	(602)
Increase in Federal operating loss carryforwards									(141)	0	0
(Decrease) increase in State valuation allowance									(51)	323	(65)
Decrease (increase) in State operating loss carryforwards and credits									11	(296)	(65)
(Increase) decrease in foreign and general business tax credits									(20)	122	73
Deferred income tax (benefit) provision									$ 1,242	$ (448)	$ (659)
State net operating loss carryforward period												12 years	20 years