Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Consolidated Balance Sheets [Abstract]
Fixed maturities, available for sale, amortized cost	$ 5,591,125	$ 5,311,457
Equity securities, available for sale, cost	$ 78,016	$ 52,396
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
Common stock, shares authorized	75,000,000	75,000,000
Common stock, shares issued	63,028,857	62,311,787
Treasury stock, shares	23,117,353	22,943,925