Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Investments:
Fixed maturity securities	$ 11,665,117	$ 11,943,956
Equity securities available for sale	399,386	376,022
Arbitrage trading account	701,223	329,077
Investment funds	793,603	809,689
Loans receivable	456,533	401,961
Real estate	588,777	606,735
Total investments	14,604,639	14,467,440
Cash and cash equivalents	945,492	905,670
Premiums and fees receivable	1,504,535	1,440,752
Due from reinsurers	1,441,389	1,450,348
Accrued investment income	126,577	127,230
Prepaid reinsurance premiums	345,329	316,309
Deferred policy acquisition costs	425,070	404,047
Real estate, furniture and equipment	271,012	267,227
Goodwill	107,529	87,865
Trading account receivables from brokers and clearing organizations	28,720	446,873
Other assets	320,342	242,135
Total assets	20,120,634	20,155,896
Liabilities:
Reserves for losses and loss expenses	9,809,843	9,751,086
Unearned premiums	2,635,995	2,474,847
Due to reinsurers	298,557	316,388
Trading account securities sold but not yet purchased	79,965	121,487
Deferred federal and foreign income taxes	104,810	82,801
Other liabilities	844,297	959,080
Junior subordinated debentures	243,258	243,206
Senior notes and other debt	1,693,279	1,871,535
Total liabilities	15,710,004	15,820,430
Equity:
Preferred stock, par value $.10 per share: Authorized 5,000,000 shares; issued and outstanding - none	0	0
Common stock, Value issued $.20 per share:Authorized 500,000,000 shares, issued and outstanding, net of treasury shares, 138,274,272 and 137,520,019 shares	47,024	47,024
Additional paid-in capital	949,926	945,166
Retained earnings	4,922,178	4,817,807
Accumulated other comprehensive income	428,592	465,631
Treasury stock, Value, 96,843,646 and 97,597,899 shares	(1,969,179)	(1,969,411)
Total stockholders' equity	4,378,541	4,306,217
Noncontrolling interests	32,089	29,249
Total equity	4,410,630	4,335,466
Total liabilities and equity	$ 20,120,634	$ 20,155,896