Noninterest Income - Gains and Losses on Derivatives (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Other Income and Expenses [Abstract]
Gains on exercises, net	$ 40,226	$ 8,875	$ 49,180	$ 20,509
Terminations	(1,045)	(826)	(1,884)	(1,726)
Changes in fair value, net	9,166	11,012	22,356	19,469
Gains on equity warrant assets, net	$ 48,347	$ 19,061	$ 69,652	$ 38,252