Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net Income	$ 34,239	$ 40,494	$ 82,726
Change in Net Unrealized Gains (Losses) on Available-for-Sale Investments:
Unrealized Gains (Losses) on Investments arising during the period, net of Deferred Tax of $14,380, $(8,748) and $3,730 in 2018, 2017 and 2016, respectively	(53,770)	23,123	(6,927)
Reclassification adjustment for Net Realized Gains (Losses) included in Net Income, net of Deferred Tax of $1,029, $5,335 and $(846) in 2018, 2017 and 2016, respectively	(2,835)	(14,100)	1,572
Change in Net Unrealized Gains (Losses) on Available-for-Sale Investments	(56,605)	9,023	(5,355)
Change in Other-Than-Temporary Impairments
Non Credit Other-Than-Temporary Impairments arising during the period, net of Deferred Tax of $34, $(16) and $27 in 2018, 2017 and 2016, respectively	(93)	40	(50)
Reclassification Adjustment for Other-Than-Temporary Impairment Credit Losses Recognized in Net Income net of Deferred Tax of $0 in 2018, 2017 and 2016, respectively	0	0	0
Change in Other-Than-Temporary Impairments	(93)	40	(50)
Change in Foreign Currency Translation Gains (Losses), net of Deferred Tax of $2,069, $(2,874) and $5,017 in 2018, 2017 and 2016, respectively	(9,567)	1,930	(9,324)
Change in Benefit Plans' Obligations, net of Deferred Tax of $68 in 2018	(204)	0	0
Other Comprehensive Income (Loss)	(66,469)	10,993	(14,729)
Comprehensive Income (Loss)	$ (32,230)	$ 51,487	$ 67,997