CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (65,382)	$ 38,401	$ (123,167)	$ 324,227
Other comprehensive income, net of tax:
Unrealized gains arising during the period, net of reclassification adjustment	66,202	24,761	179,982	352,797
Foreign currency translation adjustment	2,310	(4,610)	(1,581)	609
Total other comprehensive income, net of tax	68,512	20,151	178,401	353,406
Comprehensive income	3,130	58,552	55,234	677,633
Unrealized gains (losses) on available for sale investments, net of tax:
Other comprehensive income, net of tax:
Adjustment for reclassification of net realized gains, impairment losses and OTTI losses recognized in net income (loss)	(29,130)	(14,808)	(30,289)	(8,423)
Unrealized gains arising during the period, net of reclassification adjustment	66,202	24,761	179,982	352,797
Unrealized gains (losses) on available for sale investments, net of tax: | Unrealized gains arising during the period for which an allowance for expected credit losses has not been recognized
Other comprehensive income, net of tax:
Unrealized holding gain (loss) arising during period	95,112	39,569	210,383	361,220
Unrealized gains (losses) on available for sale investments, net of tax: | Unrealized gains (losses) arising during the period for which an allowance for expected credit losses has been recognized
Other comprehensive income, net of tax:
Unrealized holding gain (loss) arising during period	$ 220	$ 0	$ (112)	$ 0