CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Securities, available-for-sale, at fair value:
Fixed maturities, amortized cost	$ 4,185,937	$ 5,700,894
Shareholders' equity (note 15):
Common stock, par value (in dollars per share)	$ 1	$ 1
Common stock, shares authorized (in shares)	680,000	460,000
Common stock, shares issued (in shares)	205,047	205,047
Common stock, shares outstanding (in shares)	202,032	201,172
Treasury stock, shares at cost (in shares)	3,015	3,875