Condensed Consolidated Statements of Other Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Net income	$ 7,207	$ 8,296	$ 15,683	$ 15,587
Investments available-for-sale:
Net change in unrealized gains (losses) on investments available-for-sale	2,452	12,570	1,349	12,833
Related income tax expense	(977)	(5,012)	(538)	(5,117)
Net investment gains reclassified into earnings	90	32	163	52
Related income tax expense	(36)	(13)	(65)	(21)
Net effect on other comprehensive income (loss) for the period	1,529	7,577	909	7,747
Defined benefit pension plan:
Recognition of unrealized gain	349	276	699	593
Related income tax expense	(139)	(109)	(279)	(236)
Net effect on other comprehensive income for the period	210	167	420	357
Total other comprehensive income (loss)	1,739	7,744	1,329	8,104
Comprehensive income	$ 8,946	$ 16,040	$ 17,012	$ 23,691