CONSOLIDATED STATEMENTS OF OTHER COMPREHENSIVE INCOME (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Net income	$ 36,554	$ 34,102	$ 23,520
Investments available-for-sale:
Net change in unrealized gains (losses) on investments available-for-sale	(40)	26,722	(932)
Related income tax (expense) benefit	16	(10,656)	374
Net investment gains reclassified into earnings	459	292	796
Related income tax expense	(183)	(116)	(319)
Net effect on other comprehensive income (loss) for the period	252	16,242	(81)
Defined benefit pension plan:
Recognition of unrealized gain (loss)	(3,639)	(622)	188
Related income tax (expense) benefit	1,451	248	(75)
Net effect on other comprehensive income (loss) for the period	(2,188)	(374)	113
Total other comprehensive income	(1,936)	15,868	32
Comprehensive income	$ 34,618	$ 49,970	$ 23,552