Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
ASSETS:
Fixed maturities - available for sale, at market value (amortized cost: 2011, $11,731,173; 2010, $12,011,336)	$ 12,293,524	$ 12,450,469
Fixed maturities - available for sale, at fair value	113,606	180,482
Equity securities - available for sale, at market value (cost: 2011, $463,620; 2010, $363,283)	448,930	363,736
Equity securities - available for sale, at fair value	1,249,106	721,449
Short-term investments	685,332	785,279
Other invested assets (cost: 2011, $558,232; 2010, $603,681)	558,232	605,196
Cash	448,651	258,408
Total investments and cash	15,797,381	15,365,019
Accrued investment income	130,193	148,990
Premiums receivable	1,077,548	844,832
Reinsurance receivables	580,339	684,718
Funds held by reinsureds	267,295	379,616
Deferred acquisition costs	378,026	383,769
Prepaid reinsurance premiums	85,409	133,007
Deferred tax asset	332,783	149,101
Federal income taxes recoverable	41,623	124,215
Other assets	202,958	170,931
TOTAL ASSETS	18,893,555	18,384,198
LIABILITIES:
Reserve for losses and loss adjustment expenses	10,123,215	9,340,183
Future policy benefit reserve	67,187	63,002
Unearned premium reserve	1,412,778	1,455,219
Funds held under reinsurance treaties	2,528	99,213
Commission reserves	55,103	45,936
Other net payable to reinsurers	51,564	47,519
Revolving credit borrowings		50,000
5.4% Senior notes due 10/15/2014	249,858	249,812
6.6% Long term notes due 5/1/2067	238,354	238,351
Junior subordinated debt securities payable	329,897	329,897
Accrued interest on debt and borrowings	4,781	4,793
Equity index put option liability	69,729	58,467
Other liabilities	217,186	118,289
Total liabilities	12,822,180	12,100,681
Commitments and contingencies (Note 16)
SHAREHOLDERS' EQUITY:
Preferred shares, par value: $0.01; 50,000 shares authorized; no shares issued and outstanding
Common shares, par value: $0.01; 200,000 shares authorized; (2011) 66,455 and (2010) 66,017 outstanding before treasury shares	665	660
Additional paid-in capital	1,892,988	1,863,031
Accumulated other comprehensive income (loss), net of deferred income tax expense (benefit) of $112,969 at 2011 and $102,868 at 2010	366,978	332,258
Treasury shares, at cost; 12,719 shares (2011) and 11,589 shares (2010)	(1,073,970)	(981,480)
Retained earnings	4,884,714	5,069,048
Total shareholders' equity	6,071,375	6,283,517
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	$ 18,893,555	$ 18,384,198