Statutory Accounting and Regulatory Requirements (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Insurance subsidiaries
Capital and surplus	$ 323,932	$ 314,397	$ 320,388
Net income	31,059	26,969	30,484
Realized investment gains (losses)	$ 2,958	$ 2,121	$ 3,040