Condensed Consolidated Balance Sheets (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Investments
Fixed maturities, at fair value (amortized cost: 2013—$8,323; 2012—$8,222)	$ 9,169	$ 9,093
Equity securities, at fair value (cost: 2013—$2,416; 2012—$2,369)	3,801	3,373
Other invested assets	67	68
Total investments	13,037	12,534
Cash and cash equivalents	380	487
Investment income receivable	117	115
Finance receivable	76	75
Premiums receivable	1,291	1,214
Reinsurance recoverable	620	615
Prepaid reinsurance premiums	26	26
Deferred policy acquisition costs	491	470
Land, building and equipment, net, for company use (accumulated depreciation: 2013—$398; 2012—$397)	216	217
Other assets	57	61
Separate accounts	726	734
Total assets	17,037	16,548
Insurance reserves
Loss and loss expense reserves	4,240	4,230
Life policy and investment contract reserves	2,310	2,295
Unearned premiums	1,875	1,792
Other liabilities	578	660
Deferred income tax	588	453
Note payable	104	104
Long-term debt and capital lease obligations	831	827
Separate accounts	726	734
Total liabilities	11,252	11,095
Commitments and contingent liabilities (Note 12)	0	0
SHAREHOLDERS' EQUITY
Common stock, par value—$2 per share; (authorized: 2013 and 2012—500 million shares; issued and outstanding: 2013 and 2012—197 million shares)	395	394
Paid-in capital	1,146	1,134
Retained earnings	4,109	4,021
Accumulated other comprehensive income	1,362	1,129
Treasury stock at cost (2013 and 2012—34 million shares)	(1,227)	(1,225)
Total shareholders' equity	5,785	5,453
Total liabilities and shareholders' equity	$ 17,037	$ 16,548