Consolidated Statement of Cash Flows (Unaudited) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Cash flows from operating activities
Net income	$ 806	$ 839
Adjustments to reconcile net income to net cash provided by operating activities:
Net realized investment gains	(10)	(20)
Depreciation and amortization	216	208
Deferred federal income tax expense	119	153
Amortization of deferred acquisition costs	971	948
Equity in income from other investments	(114)	(122)
Change in premiums receivable	(151)	(167)
Change in reinsurance recoverables	494	218
Change in deferred acquisition costs	(984)	(964)
Change in claims and claim adjustment expense reserves	(503)	(251)
Change in unearned premium reserves	117	175
Other operating activities	(147)	(384)
Net cash provided by operating activities	814	633
Cash flows from investing activities
Proceeds from maturities of fixed maturities	1,615	1,849
Proceeds from sales of investments, fixed maturities	223	490
Proceeds from sales of investments, equity securities	15	8
Proceeds from sales of investments, other investments	203	161
Purchases of investments, fixed maturities	(2,604)	(1,824)
Purchases of investments, equity securities	(10)	(51)
Purchases of investments, real estate investments	(5)	(30)
Purchases of investments, other investments	(114)	(107)
Net (purchases) sales of short-term securities	226	(31)
Securities transactions in course of settlement	248	134
Other investing activities	(92)	(69)
Net cash provided by (used in) investing activities	(295)	530
Cash flows from financing activities
Dividends paid to shareholders	(161)	(155)
Issuance of common stock - employee share options	77	168
Treasury stock acquired - share repurchase authorization	(354)	(1,104)
Treasury stock acquired - net employee share-based compensation	(52)	(44)
Excess tax benefits from share-based payment arrangements	12	7
Net cash used in financing activities	(478)	(1,128)
Effect of exchange rate changes on cash	3	4
Net increase in cash	44	39
Cash at beginning of year	214	200
Cash at end of period	258	239
Supplemental disclosure of cash flow information
Income taxes paid	20	112
Interest paid	$ 35	$ 35