Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 7,024	$ 22,022	$ 13,080	$ 47,400
Change in unrealized gain (loss) on investments:
Net unrealized gain (loss) arising during the period	5,893	(3,912)	8,056	(3,175)
Other-than-temporary impairment loss charged to income	542	293	1,217	1,983
Call and repayment losses charged to investment income	10	19	11	55
Reclassification adjustment for net realized (gains) losses	(391)	74	(316)	267
Net change in unrealized gain (loss)	6,054	(3,526)	8,968	(870)
Deferred income taxes on above change	(2,336)	1,360	(3,460)	335
Total other comprehensive income (loss), net of income taxes	3,718	(2,166)	5,508	(535)
Comprehensive income	$ 10,742	$ 19,856	$ 18,588	$ 46,865