Noninterest Income - Gains on Equity Warrant Assets, Net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenue from Contract with Customer [Abstract]
Gains on exercises, net	$ 107,168	$ 58,186	$ 48,275
Terminations	(3,502)	(5,964)	(4,422)
Changes in fair value, net	34,412	36,920	10,702
Gains on equity warrant assets, net	$ 138,078	$ 89,142	$ 54,555