Condensed Financial Information of Parent Company (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Cash Flows from Operating Activities
Net Income	$ 452	$ 298	$ 419	$ 509	$ 620	$ 572	$ 518	$ 464	$ 1,678	$ 2,174	$ 2,183
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities
Realized Investment Gains, Net									(288)	(426)	(23)
Other, Net									(52)	(117)	(147)
NET CASH PROVIDED BY (USED IN) OPERATING ACTIVITIES									1,878	2,331	2,417
Cash Flows from Investing Activities
Proceeds from Fixed Maturities - Sales									1,730	2,287	3,029
Proceeds from Fixed Maturities - Maturities, Calls and Redemptions									3,540	2,856	2,578
Proceeds from Sales of Equity Securities									167	129	394
Purchases of Fixed Maturities									(5,014)	(5,176)	(7,372)
Investments in Other Invested Assets, Net									285	173	(37)
Decrease (Increase) in Short Term Investments, Net									11	38	563
Other, Net										6	(6)
NET CASH PROVIDED BY (USED IN) INVESTING ACTIVITIES									580	67	(856)
Cash Flows from Financing Activities
Repayment of Long Term Debt									(400)	0	0
Proceeds from Issuance of Common Stock Under Stock-Based Employee Compensation Plans									80	74	34
Repurchase of Shares									(1,707)	(2,003)	(1,060)
Dividends Paid to Shareholders									(450)	(472)	(487)
NET CASH USED IN FINANCING ACTIVITIES									(2,470)	(2,379)	(1,566)
Net Increase in Cash									(12)	19	(5)
Cash at Beginning of Year				70				51	70	51	56
CASH AT END OF YEAR	58				70				58	70	51
Parent Company [Member]
Cash Flows from Operating Activities
Net Income									1,678	2,174	2,183
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities
Equity in Net Income of Consolidated Subsidiaries									(1,912)	(2,371)	(2,319)
Realized Investment Gains, Net									(9)	(16)	(88)
Other, Net									(28)	(14)	111
NET CASH PROVIDED BY (USED IN) OPERATING ACTIVITIES									(271)	(227)	(113)
Cash Flows from Investing Activities
Proceeds from Fixed Maturities - Sales									2	3	5
Proceeds from Fixed Maturities - Maturities, Calls and Redemptions									456	202	126
Proceeds from Sales of Equity Securities									9	0	308
Purchases of Fixed Maturities									(257)	(73)	(651)
Investments in Other Invested Assets, Net									0	33	0
Decrease (Increase) in Short Term Investments, Net									(219)	199	543
Dividends Received from Consolidated Insurance Subsidiaries									2,700	2,200	1,200
Distributions Received from Consolidated Non-Insurance Subsidiaries									1	4	35
Other, Net									56	60	60
NET CASH PROVIDED BY (USED IN) INVESTING ACTIVITIES									2,748	2,628	1,626
Cash Flows from Financing Activities
Repayment of Long Term Debt									(400)	0	0
Proceeds from Issuance of Common Stock Under Stock-Based Employee Compensation Plans									80	74	34
Repurchase of Shares									(1,707)	(2,003)	(1,060)
Dividends Paid to Shareholders									(450)	(472)	(487)
NET CASH USED IN FINANCING ACTIVITIES									(2,477)	(2,401)	(1,513)
Net Increase in Cash									0	0	0
Cash at Beginning of Year				0				0	0	0	0
CASH AT END OF YEAR	$ 0				$ 0				$ 0	$ 0	$ 0