Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Consolidated Statements of Comprehensive Income (Loss) [Abstract]
Net income (loss)	$ (11,553)	$ 6,526	$ 21,863
Other comprehensive income (loss):
Change in net actuarial gain (loss)	548	(145)	43
Tax effect on change in net actuarial gain (loss)	(192)	51	(15)
Unrealized holding (losses) gains arising during the period	9,117	6,019	(10,191)
Tax effect on unrealized holding (losses) gains arising during the period	(3,191)	(2,107)	3,567
Reclassification adjustment for gains included in net realized gains	(6,799)	(1,331)	(5,826)
Tax effect on reclassification adjustment for gains included in income tax expense	2,380	466	2,039
Other comprehensive income (loss), net of tax	1,863	2,953	(10,383)
Comprehensive income (loss)	$ (9,690)	$ 9,479	$ 11,480