Condensed Financial Information (Parent Company) (Details 2) (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	Dec. 31, 2012 Parent Company [Member]	Dec. 31, 2011 Parent Company [Member]	Dec. 31, 2010 Parent Company [Member]	Dec. 31, 2009 Parent Company [Member]
Cash flows from operating activities
Net income (loss)	$ 136	$ (957)	$ 2,303	$ (120)	$ 988	$ 3,450	$ 1,093	$ 884	$ 1,362	$ 6,415	$ 2,663	$ 1,324	$ 6,423	$ 2,667
Earnings of subsidiaries												(3,444)	(6,979)	(3,318)
Dividends from subsidiaries												3,177	2,578	916
Goodwill impairment									1,868	0	0	1,384	0	0
Other, net												177	697	376
Net cash provided by operating activities									17,160	10,273	7,985	2,618	2,719	641
Cash flows from investing activities
Sales of fixed maturity securities									103,823	104,302	86,529	5,645	3,265	7,422
Purchases of fixed maturity securities									(115,793)	(116,939)	(100,713)	(6,200)	(4,787)	(6,542)
Sales of equity securities									1,140	2,006	1,371	2	1	5
Cash received in connection with freestanding derivatives									1,933	2,815	1,814	197	257	200
Cash paid in connection with freestanding derivatives									(3,258)	(3,478)	(2,548)	(203)	(276)	(450)
Sales of businesses									29	54	0	0	180	0
Purchases of businesses												0	0	(7,196)
Expense paid on behalf of subsidiaries												(80)	(75)	(72)
Repayments of loans to subsidiaries												175	1,275	300
Issuances of loans to subsidiaries												(175)	0	0
Investment in preferred stock of subsidiary												0	(250)	(50)
Returns of capital from subsidiaries												9	591	54
Capital contributions to subsidiaries												(1,223)	(1,439)	(374)
Net change in short-term investments									593	(7,949)	3,033	372	(620)	271
Other, net									(158)	(169)	(186)	(48)	(10)	(35)
Net cash used in investing activities									(11,929)	(22,218)	(18,303)	(1,529)	(1,888)	(6,467)
Cash flows from financing activities
Net change in payables for collateral under securities loaned and other transactions									(29)	6,444	3,076	(1,180)	520	233
Long-term debt issued									750	1,346	5,090	750	0	2,987
Long-term debt repaid									(1,702)	(2,042)	(1,061)	(797)	(750)	0
Cash received (paid) in connection with collateral financing arrangements									(44)	37	0	(44)	37	0
Common stock issued, net of issuance costs									1,000	2,950	3,529	1,000	2,950	3,576
Redemption of convertible preferred stock									0	(2,805)	0	0	(2,805)	0
Preferred stock redemption premium	0	0	0	0	0	0	0	(146)	0	(146)	0	0	(146)	0
Dividends on preferred stock									(122)	(122)	(122)	(122)	(122)	(122)
Dividends on common stock									(811)	(787)	(784)	(811)	(787)	(784)
Other, net									609	212	(266)	(6)	(43)	(119)
Net cash (used in) provided by financing activities									35	9,382	13,381	(1,210)	(1,146)	5,771
Change in cash and cash equivalents												(121)	(315)	(55)
Cash and cash equivalents, beginning of year													309	624	679
Cash and cash equivalents, end of year												188	309	624
Supplemental disclosures of cash flow information:
Net cash paid (received) for Interest									1,335	1,565	1,489	937	997	808
Net cash paid (received) for Income tax									554	676	(23)	24	(659)	(474)
Business acquisitions:
Assets acquired									595	327	125,728	0	0	125,728
Liabilities assumed									(579)	(94)	(109,306)	0	0	(109,306)
Redeemable and non-redeemable noncontrolling interests assumed	0				0				0	0	(130)	0	0	(130)
Net assets acquired	16				233				16	233	16,292	0	0	16,292
Cash paid, excluding transaction costs of $0, $0 and $88, respectively									(16)	(233)	(7,196)	0	0	(7,196)
Other purchase price adjustments	0				0				0	0	98	0	0	98
Securities issued	0				0				0	0	9,194	0	0	9,194
Cash paid excluding transaction costs									0	0	88	0	0	88
Dividends from subsidiaries												203	170	874
Returns of capital from subsidiaries												356	47	0
Capital contributions to subsidiaries												559	316	0
Assumption of long-term debt from subsidiary												2,000	0	0
Investment in preferred stock of subsidiary												2,000	0	0
Issuance of long-term debt to subsidiary												750	0	0
Issuance of loan to subsidiary												750	0	0
Allocation of interest expense to subsidiary												33	29	30
Allocation of interest income to subsidiary												$ 76	$ 68	$ 46