CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Cash Flows from Operating Activities
Net Income	$ 1,235	$ 910
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities
Increase (Decrease) in Unpaid Losses and Loss Expenses, Net	(299)	279
Increase in Unearned Premiums, Net	158	115
Increase in Premiums Receivable	(130)	(118)
Change in Income Tax Payable or Recoverable	27	(100)
Amortization of Premiums and Discounts on Fixed Maturities	91	77
Depreciation	28	26
Realized Investment Gains, Net	(317)	(103)
Other, Net	(229)	(200)
Net Cash Provided by Operating Activities	564	886
Cash Flows from Investing Activities
Proceeds from Fixed Maturities - Sales	1,138	1,176
Proceeds from Fixed Maturities - Maturities, Calls and Redemptions	2,353	1,946
Proceeds from Sales of Equity Securities	273	63
Purchases of Fixed Maturities	(4,053)	(3,477)
Purchases of Equity Securities	(92)	(70)
Investments in Other Invested Assets, Net	280	179
Decrease (Increase) in Short Term Investments, Net	514	(117)
Change in Receivable or Payable from Security Transactions Not Settled, Net	165	221
Purchases of Property and Equipment, Net	(25)	(21)
Net Cash Provided by (Used In) Investing Activities	553	(100)
Cash Flows from Financing Activities
Repayment of Long Term Debt	(275)
Decrease in Funds Held Under Deposit Contracts	(4)	(6)
Proceeds from Issuance of Common Stock Under Stock-Based Employee Compensation Plans	36	60
Repurchase of Shares	(634)	(618)
Dividends Paid to Shareholders	(223)	(219)
Net Cash Used in Financing Activities	(1,100)	(783)
Net Increase in Cash	17	3
Cash at Beginning of Year	50	58
Cash at End of Period	$ 67	$ 61