Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2011
Consolidated Balance Sheets [Abstract]
Fixed maturities, available for sale, amortized cost	$ 5,041,475	$ 4,984,389
Equity securities, available for sale, cost	$ 24,346	$ 23,070
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	1,000,000	1,000,000
Preferred stock, shares issued	0	0
Common stock, par value	$ 0.001	$ 0.001	$ 0.001
Common stock, shares authorized	75,000,000	75,000,000
Common stock, shares issued	62,001,513	61,803,462
Treasury stock, shares	22,228,150	22,028,030	21,813,196