Derivative Financial Instruments - Effect of Derivative Instruments on Consolidated Statements of Income Derivative in Fair Value Hedging Relationship (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Derivative in fair value hedging relationship | Interest income–loans
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized on Derivative	$ 0	$ 0	$ 0
Derivative in fair value hedging relationship | Interest rate contracts | Interest income–loans
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized on Derivative	(20,962)	(11,380)	(852)
Derivative in fair value hedging relationship | Interest rate contracts | Interest income–loans
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized on Derivative	20,962	11,380	852
Derivatives not designated as hedging instruments | Mortgage loan contracts | Other income – gain on sale of loans
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized on Derivative	$ 819	$ 91	$ (5)