Consolidated Statements of Comprehensive Income (Unaudited) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Statement of Comprehensive Income [Abstract]
Net income	$ 7,371,000	$ 14,052,000	$ 54,771,000	$ 48,102,000
Change in unrealized (losses) gains on investments:
Net unrealized (losses) gains arising during the period	(6,021,000)	(1,542,000)	(9,196,000)	4,305,000
Other-than-temporary impairment losses	1,886,000	0	3,869,000	0
Call and repayment losses charged to investment income	15,000	4,000	70,000	21,000
Reclassification adjustment for realized losses (gains)	296,000	(3,294,000)	563,000	(4,465,000)
Net change in unrealized losses	(3,824,000)	(4,832,000)	(4,694,000)	(139,000)
Deferred income taxes on above change	1,476,000	1,864,000	1,811,000	54,000
Total other comprehensive loss, net of income taxes	(2,348,000)	(2,968,000)	(2,883,000)	(85,000)
Comprehensive income	$ 5,023,000	$ 11,084,000	$ 51,888,000	$ 48,017,000