Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Statement of Comprehensive Income [Abstract]
Net (loss) income	$ (18,449)	$ (6,593)	$ 16,582	$ (25,042)	$ 23,619
Unrealized gain (loss) on available-for-sale securities:
Unrealized gain (loss) arising during the period	40,002	(42,248)	5,423	(2,246)	11,596
Reclassification adjustment for (gain) loss included in net (loss) income	(1,419)	0	0	(1,419)	(147)
Total change in unrealized gain (loss) on available-for-sale securities	38,583	(42,248)	5,423	(3,665)	11,449
Total other comprehensive income (loss)	38,583	(42,248)	5,423	(3,665)	11,449
Comprehensive income (loss)	$ 20,134	$ (48,841)	$ 22,005	$ (28,707)	$ 35,068