Noninterest Income - Gains on Equity Warrant Assets, Net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Gains on exercises, net	$ 179,648	$ 107,168	$ 58,186
Terminations	(1,948)	(3,502)	(5,964)
Changes in fair value, net	59,728	34,412	36,920
Gains on equity warrant assets, net	$ 237,428	$ 138,078	$ 89,142