CONSOLIDATED BALANCE SHEETS (Unaudited) (Parenthetical) (USD $) In Thousands, except Share data	Sep. 30, 2011	Dec. 31, 2010
Securities, available-for-sale, at fair value:
Fixed maturities, amortized cost	$ 6,255,817	$ 7,366,808
Shareholders' equity:
Common stock, par value (in dollars per share)	$ 1	$ 1
Common stock, shares authorized (in shares)	460,000,000	460,000,000
Common stock, shares issued (in shares)	205,046,780	205,046,780
Common stock, shares outstanding (in shares)	201,171,528	200,449,588
Treasury stock, shares at cost (in shares)	3,875,252	4,597,192