Noninterest Income - Foreign Exchange Fees (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 1,056,842	$ 880,951	$ 511,656
Revenue not from contracts with customer	783,306	340,528	233,328
Foreign exchange fees	178,733	159,262	138,812
Spot contract commissions
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	157,852	145,915	127,459
Forward contract commissions
Disaggregation of Revenue [Line Items]
Revenue not from contracts with customer	19,849	13,068	10,940
Option premium fees
Disaggregation of Revenue [Line Items]
Revenue not from contracts with customer	$ 1,032	$ 279	$ 413