Noninterest Income - Client Investment Fees (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 328,139	$ 222,440
Sweep money market fees
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	10,461	23,049
Asset management fees
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	9,020	9,137
Repurchase agreement fees
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	584	11,207
Client investment fees
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 20,065	$ 43,393