Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net Income (Loss)	$ (1,738)	$ 30,878
Change in Net Unrealized Gains (Losses) on Available-For-Sale Investments:
Unrealized Gains(Losses) on Investments arising during the period, net of Deferred Tax	46,289	(34,305)
Reclassification adjustment for Net Realized Gains (Losses) included in Net Income net of Deferred Tax	189	(1,733)
Change in Net Unrealized Gains (Losses) on Investments	46,478	(36,038)
Change in Other-Than-Temporary Impairments
Non Credit Other-Than-Temporary Impairments arising during the period, net of Deferred Tax	(16)	(30)
Reclassification Adjustment for Other-Than-Temporary Impairment Credit Losses Recognized in Net Income net of Deferred Tax	0	0
Change in Other-Than-Temporary Impairments	(16)	(30)
Change in Foreign Currency Translation Gains, net of Deferred Tax	3,821	2,228
Other Comprehensive Income (Loss)	50,283	(33,840)
Comprehensive Income (Loss)	$ 48,545	$ (2,962)