CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Assets
Fixed maturities, available for sale, at fair value (Amortized cost 2012: $11,280,366; 2011: $10,821,338)	$ 11,504,448	$ 10,940,100
Equity securities, available for sale, at fair value (Cost 2012: $609,718; 2011: $699,566)	631,731	677,560
Other investments, at fair value	798,233	699,320
Short-term Investments, at fair value and amortized cost	71,277	149,909
Total investments	13,005,689	12,466,889
Cash and cash equivalents	751,011	981,849
Restricted cash and cash equivalents	121,740	100,989
Accrued interest receivable	97,417	98,346
Insurance and reinsurance premium balances receivable	1,888,238	1,413,839
Reinsurance recoverable on unpaid and paid losses	1,792,358	1,770,329
Deferred acquisition costs	502,413	407,527
Prepaid reinsurance premiums	271,262	238,623
Receivable for investments sold	596	3,006
Goodwill and intangible assets	98,203	99,590
Other assets	192,485	225,072
Total assets	18,721,412	17,806,059
Liabilities
Reserve for losses and loss expenses	8,600,651	8,425,045
Unearned premiums	2,958,223	2,454,462
Insurance and reinsurance balances payable	211,704	206,539
Senior notes	994,951	994,664
Other liabilities	145,188	129,329
Payable for investments purchased	112,855	151,941
Total liabilities	13,023,572	12,361,980
Commitments and contingencies
Shareholders' equity
Preferred shares - Series A, B and C	502,843	500,000
Common shares (2012: 171,468; 2011: 170,159 shares issued and 2012: 122,773; 2011: 125,588 shares outstanding)	2,141	2,125
Additional paid-in capital	2,153,467	2,105,386
Accumulated other comprehensive income	240,939	128,162
Retained earnings	4,383,405	4,155,392
Treasury shares, at cost (2012: 48,695; 2011: 44,571 shares)	(1,584,955)	(1,446,986)
Total shareholders' equity	5,697,840	5,444,079
Total liabilities and shareholders' equity	$ 18,721,412	$ 17,806,059