Consolidated Statements of Cash Flows (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Cash Flows from Operating Activities
Net Income	$ 1,545	$ 1,678	$ 2,174
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities
Increase in Unpaid Losses and Loss Expenses, Net	691	361	145
Increase in Unearned Premiums, Net	32	114	21
Decrease (Increase) in Premiums Receivable	(24)	(63)	3
Change in Income Tax Payable or Recoverable	(53)	(102)	178
Deferred Income Tax	32	25	136
Amortization of Premiums and Discounts on Fixed Maturities	163	147	154
Depreciation	54	58	63
Realized Investment Gains, Net	(193)	(288)	(426)
Other, Net	52	(52)	(117)
NET CASH PROVIDED BY OPERATING ACTIVITIES	2,299	1,878	2,331
Cash Flows from Investing Activities
Proceeds from Fixed Maturities - Sales	2,271	1,730	2,287
Proceeds from Fixed Maturities - Maturities, Calls and Redemptions	4,290	3,540	2,856
Proceeds from Sales of Equity Securities	160	167	129
Purchases of Fixed Maturities	(7,247)	(5,014)	(5,176)
Purchases of Equity Securities	(112)	(95)	(156)
Investments in Other Invested Assets, Net	293	285	173
Decrease (Increase) in Short Term Investments, Net	(629)	11	38
Increase (Decrease) in Net Payable from Security Transactions not Settled	45	8	(24)
Purchases of Property and Equipment, Net	(43)	(52)	(54)
Other, Net			(6)
NET CASH PROVIDED BY (USED IN) INVESTING ACTIVITIES	(972)	580	67
Cash Flows from Financing Activities
Repayment of Long Term Debt		(400)
Increase (Decrease) in Funds Held under Deposit Contracts	(12)	7	22
Proceeds from Issuance of Common Stock Under Stock-Based Employee Compensation Plans	74	80	74
Repurchase of Shares	(959)	(1,707)	(2,003)
Dividends Paid to Shareholders	(438)	(450)	(472)
NET CASH USED IN FINANCING ACTIVITIES	(1,335)	(2,470)	(2,379)
Net Increase (Decrease) in Cash	(8)	(12)	19
Cash at Beginning of Year	58	70	51
CASH AT END OF YEAR	$ 50	$ 58	$ 70