Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
ASSETS:
Fixed maturity investments available for sale, at fair value (amortized cost: 2012: $0; 2011: $226,397)	$ 0	$ 244,016
Fixed maturity investments trading, at fair value (amortized cost: 2012: $6,473,429; 2011: $6,207,991)	6,626,454	6,254,686
Equity securities trading, at fair value (cost: 2012: 480,312; 2011: $356,370)	523,949	367,483
Other invested assets	783,534	540,409
Total investments	7,933,937	7,406,594
Cash and cash equivalents	681,879	633,996
Restricted cash	183,485	82,608
Insurance balances receivable	846,900	652,158
Prepaid reinsurance	277,406	226,721
Reinsurance recoverable	1,141,110	1,002,919
Accrued investment income	29,135	38,263
Net deferred acquisition costs	108,010	100,334
Goodwill	268,376	268,376
Intangible assets	51,365	53,898
Balances receivable on sale of investments	418,879	580,443
Net deferred tax assets	25,580	22,646
Other assets	63,884	53,202
Total assets	12,029,946	11,122,158
LIABILITIES:
Reserve for losses and loss expenses	5,645,549	5,225,143
Unearned premiums	1,218,021	1,078,412
Reinsurance balances payable	136,264	124,539
Balances due on purchases of investments	759,934	616,728
Senior notes	798,215	797,949
Dividends payable	0	14,302
Accounts payable and accrued liabilities	145,628	116,063
Total liabilities	8,703,611	7,973,136
SHAREHOLDERS' EQUITY:
Common shares, 2012: par value CHF 12.64 per share and 2011: par value CHF 14.03 per share, (2012: 36,369,868; 2011: 40,003,642 shares issued and 2012: 34,797,781; 2011: 37,742,131 shares outstanding)	454,980	557,153
Additional paid-in capital	0	78,225
Treasury shares, at cost (2012: 1,572,087; 2011: 2,261,511)	(113,818)	(136,590)
Retained earnings	2,985,173	2,635,750
Accumulated other comprehensive income: net unrealized gains on investments, net of tax	0	14,484
Total shareholders' equity	3,326,335	3,149,022
Total liabilities and shareholders' equity	$ 12,029,946	$ 11,122,158