Noninterest Income - Investment Banking Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Underwriting fees	$ 352,951	$ 153,306	$ 0
Advisory fees	40,006	37,846	0
Private placements and other	21,028	4,025	0
Total investment banking revenue	$ 413,985	$ 195,177	$ 0

Includes (1) underwriting revenue (the spread between the resale price received and the cost of the securities and related expenses) generated through the purchasing, distributing and reselling of new issues of securities (alternatively, could be a secondary offering of a large block of previously issued securities); and (2) fees earned for mergers, acquisitions, divestitures, restructurings, and other types of financial advisory services.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.13(b),(d))
-URI http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration