Derivative Financial Instruments - Derivative Financial Instruments and the Amount and Location of the Net Gains or Losses Recognized in the Statements of Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Derivative Instruments Gain Loss [Line Items]
Net gains (losses) recognized in the statements of income	$ 35,482	$ 19,455	$ 8,353
Interest Rate Lock Commitments | Mortgage Banking Income
Derivative Instruments Gain Loss [Line Items]
Net gains (losses) recognized in the statements of income	22,348	12,185	3,534
Forward Commitments | Mortgage Banking Income
Derivative Instruments Gain Loss [Line Items]
Net gains (losses) recognized in the statements of income	(4,274)	(2,340)	821
Interest Rate Swap Agreements | Other Noninterest Income
Derivative Instruments Gain Loss [Line Items]
Net gains (losses) recognized in the statements of income	15,468	7,172	1,835
Foreign Exchange Contracts | Other Noninterest Income
Derivative Instruments Gain Loss [Line Items]
Net gains (losses) recognized in the statements of income	$ 1,940	2,891	3,163
Conversion Rate Swap Agreement | Investment Securities Gains (Losses), Net
Derivative Instruments Gain Loss [Line Items]
Net gains (losses) recognized in the statements of income		$ (453)	$ (1,000)