Consolidated Statements of Comprehensive Income (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Statement of Comprehensive Income [Abstract]
Net income	$ 14,052	$ 13,378	$ 48,102	$ 50,000
Change in unrealized gain on investments:
Unrealized gain (loss) arising during the period	(1,542)	439	4,305	(744)
Call and repayment losses charged to investment income	4	3	21	21
Reclassification adjustment for net realized gains	(3,294)	(31)	(4,465)	(43)
Net change in unrealized (loss) gain	(4,832)	411	(139)	(766)
Deferred income taxes on above change	1,864	(137)	54	317
Total other comprehensive (loss) income	(2,968)	274	(85)	(449)
Comprehensive income	$ 11,084	$ 13,652	$ 48,017	$ 49,551