Derivatives and Hedging - Free Standing Derivative Instruments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Futures contracts | Mortgage banking income and corporate and correspondent investment sales
Derivative Instruments, Gain (Loss) [Line Items]
Derivative instruments not designated as hedging instruments, gain (loss), net	$ (793)	$ (579)
Interest rate lock commitments | Mortgage banking income
Derivative Instruments, Gain (Loss) [Line Items]
Derivative instruments not designated as hedging instruments, gain (loss), net	9,322	1,146
Option contracts related to mortgage servicing rights | Mortgage banking income
Derivative Instruments, Gain (Loss) [Line Items]
Derivative instruments not designated as hedging instruments, gain (loss), net	1,528	294
Forward contracts related to residential mortgage loans held for sale | Mortgage banking income
Derivative Instruments, Gain (Loss) [Line Items]
Derivative instruments not designated as hedging instruments, gain (loss), net	(5,907)	(89)
Interest rate contracts for customers | Corporate and correspondent investment sales
Derivative Instruments, Gain (Loss) [Line Items]
Derivative instruments not designated as hedging instruments, gain (loss), net	4,137	3,428
Purchased equity option related to equity-linked CDs | Other expense
Derivative Instruments, Gain (Loss) [Line Items]
Derivative instruments not designated as hedging instruments, gain (loss), net	(1,888)	(1,017)
Written equity option related to equity-linked CDs | Other expense
Derivative Instruments, Gain (Loss) [Line Items]
Derivative instruments not designated as hedging instruments, gain (loss), net	1,624	996
Forward and swap contracts related to commercial loans | Other income
Derivative Instruments, Gain (Loss) [Line Items]
Derivative instruments not designated as hedging instruments, gain (loss), net	25,981	2,696
Spot contracts related to commercial loans | Other income
Derivative Instruments, Gain (Loss) [Line Items]
Derivative instruments not designated as hedging instruments, gain (loss), net	771	(502)
Foreign currency exchange contracts for customers | Corporate and correspondent investment sales
Derivative Instruments, Gain (Loss) [Line Items]
Derivative instruments not designated as hedging instruments, gain (loss), net	$ 4,701	$ 3,851