CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Cash Flows from Operating Activities
Net Income	$ 656	$ 506
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities
Increase (Decrease) in Unpaid Losses and Loss Expenses, Net	(270)	56
Increase (Decrease) in Unearned Premiums, Net	53	(2)
Decrease in Premiums Receivable	4	37
Change in Income Tax Payable or Recoverable	168	48
Amortization of Premiums and Discounts on Fixed Maturities	44	37
Depreciation	14	13
Realized Investment Gains, Net	(138)	(56)
Other, Net	(232)	(267)
Net Cash Provided by Operating Activities	299	372
Cash Flows from Investing Activities
Proceeds from Fixed Maturities - Sales	450	805
Proceeds from Fixed Maturities - Maturities, Calls and Redemptions	943	733
Proceeds from Sales of Equity Securities	106	45
Purchases of Fixed Maturities	(1,909)	(1,704)
Purchases of Equity Securities	(36)	(37)
Investments in Other Invested Assets, Net	139	47
Decrease in Short Term Investments, Net	659	121
Change in Receivable or Payable from Security Transactions Not Settled, Net	(244)	21
Purchases of Property and Equipment, Net	(15)	(10)
Net Cash Provided by Investing Activities	93	21
Cash Flows from Financing Activities
Decrease in Funds Held Under Deposit Contracts	(4)	(2)
Proceeds from Issuance of Common Stock Under Stock-Based Employee Compensation Plans	34	53
Repurchase of Shares	(309)	(325)
Dividends Paid to Shareholders	(108)	(107)
Net Cash Used in Financing Activities	(387)	(381)
Net Increase in Cash	5	12
Cash at Beginning of Year	50	58
Cash at End of Period	$ 55	$ 70