Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Per Share data, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Statement Of Financial Position [Abstract]
Amortized cost of investments	$ 128,065	$ 130,342
Allowance for premiums and fees receivable	$ 434	$ 306
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	10,000	10,000
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	75,000	75,000
Common stock, shares issued	40,967	40,962
Common stock, shares outstanding	40,967	40,962