Noninterest Income - Gains and Losses on Investments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Other Income and Expenses [Abstract]
Total net gains on non-marketable and other equity securities	$ 34,868	$ 47,973	$ 19,758	$ 80,631
(Losses) gains on sales of available-for-sale securities, net	0	(275)	61,165	(3,905)
Gains on investment securities, net	$ 34,868	$ 47,698	$ 80,923	$ 76,726