Summary of Significant Accounting Policies (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2011 As Reported [Member]	Dec. 31, 2009 As Reported [Member]	Dec. 31, 2011 Adjustment [Member]	Dec. 31, 2009 Adjustment [Member]	Dec. 31, 2011 As Adjusted [Member]
Adjustments to the financial statement Consolidated Balance Sheet
Deferred income taxes	$ 29,521	$ 30,048		$ 29,286		$ 762		$ 30,048
Deferred policy acquisition costs	18,419	16,578		18,756		(2,178)		16,578
Total assets	1,220,946	1,143,973		1,148,509		(4,536)		1,143,973
Reinsurance premiums payable	456	1,226				1,226		1,226
Insurance-related assessments	22,244	19,071		21,506		(2,435)		19,071
Accounts payable and other liabilities	25,649	23,721		25,633		(1,912)		23,721
Total liabilities	839,724	794,536		797,657		(3,121)		794,536
Shareholders' equity	381,222	349,437	328,721	350,852	306,133	(1,415)	304,748	349,437
Total liabilities and shareholders' equity	$ 1,220,946	$ 1,143,973		$ 1,148,509		$ (4,536)		$ 1,143,973