Income Taxes (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Current income tax:
Federal									$ 229	$ 250	$ (224)
State and local									25	21	13
Foreign									31	23	32
Total current income tax									285	294	(179)
Deferred income tax:
Federal									37	90	483
State and local									15	1	(5)
Foreign									(2)	(8)	(6)
Total deferred income tax									50	83	472
Total income tax provision (benefit)									335	377	293
Geographic sources of pretax income (loss)
United States									1,161	1,350	1,305
Foreign									77	97	164
Income from continuing operations before income tax provision	418	199	299	322	326	326	409	386	1,238	1,447	1,469
Reconciliation of the income tax provision
Tax at U.S. statutory rate (as a percent)									35.00%	35.00%	35.00%
Changes in taxes resulting from:
Dividend exclusion (as a percent)									(5.90%)	(8.50%)	(4.60%)
Tax-exempt interest income (as a percent)									(1.70%)	(1.30%)	(1.10%)
Foreign tax credits, net of addback (as a percent)									(3.20%)	(2.20%)	(1.70%)
Low income housing credits (as a percent)									(3.00%)	(1.10%)	(1.60%)
Taxes applicable to prior years (as a percent)									(2.50%)	0.20%	(3.20%)
State taxes, net of federal benefit (as a percent)									2.50%	1.00%	0.20%
Net income (loss) attributable to noncontrolling interests (as a percent)									3.60%	2.60%	(3.90%)
Other, net (as a percent)									2.30%	0.40%	0.80%
Income tax provision (as a percent)									27.10%	26.10%	19.90%
Accumulated earnings of foreign subsidiaries									85
Aggregate U.S. federal taxes not provided on earnings of foreign subsidiaries									$ 1