Noninterest Income - Foreign Exchange 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
Revenue not from contract with customer	416,041	79,494
Foreign exchange fees	57,393	47,505
Spot contract commissions
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	54,929	40,934
Forward contract commissions
Disaggregation of Revenue [Line Items]
Revenue not from contract with customer	2,348	6,339
Option premium fees
Disaggregation of Revenue [Line Items]
Revenue not from contract with customer	$ 116	$ 232