CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Statement Of Income And Comprehensive Income [Abstract]
Net income (loss)	$ 22,704	$ (63,460)	$ (181,949)	$ (71,206)
Amounts related to available for sale securities:
Change in net unrealized gain or loss	64,659	47,185	(1,111)	90,661
Reclassification adjustment for amounts included in net income (loss)		1,365	66,864	1,365
Amounts related to cash flow hedges:
Change in net unrealized gain or loss	(567)	(6,746)	(21,818)	(15,297)
Reclassification adjustment for amounts included in net income (loss)	938	(6,351)	1,418	(16,922)
Other comprehensive income	65,030	35,453	45,353	59,807
Comprehensive income (loss)	$ 87,734	$ (28,007)	$ (136,596)	$ (11,399)