Derivatives and Hedging - Derivatives by Balance Sheet Location (Details) - USD ($) $ in Thousands		Sep. 30, 2020		Dec. 31, 2019
Derivatives, Fair Value [Line Items]
Derivative assets		$ 46,217		$ 41,390
Derivative liabilities		174,188		94,979
Derivatives designated as hedging instrument
Derivatives, Fair Value [Line Items]
Derivative assets	[1]	12,408		10,735
Derivative liabilities	[2]	3,924		3,218
Derivatives designated as hedging instrument | Fair value hedges
Derivatives, Fair Value [Line Items]
Derivative assets	[1]	12,408		10,633
Derivative liabilities	[2]	837		354
Derivatives designated as hedging instrument | Fair value hedges | Interest rate swaps related to long-term debt
Derivatives, Fair Value [Line Items]
Derivative, notional amount		3,496,086		3,623,950
Derivative assets	[1]	12,408		10,633
Derivative liabilities	[2]	837		354
Derivatives designated as hedging instrument | Cash flow hedges
Derivatives, Fair Value [Line Items]
Derivative assets	[1]	0		102
Derivative liabilities	[2]	3,087		2,864
Derivatives designated as hedging instrument | Cash flow hedges | Swaps related to commercial loans
Derivatives, Fair Value [Line Items]
Derivative, notional amount		10,000,000		10,000,000
Derivative assets	[1]	0		0
Derivative liabilities	[2]	0		0
Derivatives designated as hedging instrument | Cash flow hedges | Swaps related to FHLB advances
Derivatives, Fair Value [Line Items]
Derivative, notional amount		120,000		120,000
Derivative assets	[1]	0		0
Derivative liabilities	[2]	3,000		2,864
Derivatives designated as hedging instrument | Cash flow hedges | Foreign exchange contracts
Derivatives, Fair Value [Line Items]
Derivative, notional amount		1,178		2,597
Derivative assets	[1]	0		102
Derivative liabilities	[2]	87		0
Free-standing derivatives not designated as hedging instrument
Derivatives, Fair Value [Line Items]
Derivative assets	[1]	769,712		344,247
Derivative liabilities	[2]	202,119		132,682
Free-standing derivatives not designated as hedging instrument | Forward contracts related to held for sale mortgages
Derivatives, Fair Value [Line Items]
Derivative, notional amount		794,989		289,990
Derivative assets	[1]	638		148
Derivative liabilities	[2]	1,993		514
Free-standing derivatives not designated as hedging instrument | Option contracts related to mortgage servicing rights
Derivatives, Fair Value [Line Items]
Derivative, notional amount		0		60,000
Derivative assets	[1]	0		38
Derivative liabilities	[2]	0		0
Free-standing derivatives not designated as hedging instrument | Interest rate lock commitments
Derivatives, Fair Value [Line Items]
Derivative, notional amount		636,349		146,941
Derivative assets	[1]	16,305		3,088
Derivative liabilities	[2]	0		0
Free-standing derivatives not designated as hedging instrument | Purchased equity option related to equity-linked CDs
Derivatives, Fair Value [Line Items]
Derivative, notional amount		50,831		152,130
Derivative assets	[1]	774		4,460
Derivative liabilities		0	[2]	0
Free-standing derivatives not designated as hedging instrument | Written equity option related to equity-linked CDs
Derivatives, Fair Value [Line Items]
Derivative, notional amount		41,065		128,620
Derivative assets	[1]	0		0
Derivative liabilities	[2]	625		3,765
Free-standing derivatives not designated as hedging instrument | Forwards and swaps related to commercial loans
Derivatives, Fair Value [Line Items]
Derivative, notional amount		385,230		443,493
Derivative assets	[1]	2,678		167
Derivative liabilities	[2]	1,883		3,872
Free-standing derivatives not designated as hedging instrument | Spots related to commercial loans
Derivatives, Fair Value [Line Items]
Derivative, notional amount		336		48,626
Derivative assets	[1]	0		7
Derivative liabilities	[2]	1		68
Free-standing derivatives not designated as hedging instrument | Swap associated with sale of Visa, Inc. Class B shares
Derivatives, Fair Value [Line Items]
Derivative, notional amount		172,368		161,904
Derivative assets	[1]	0		0
Derivative liabilities	[2]	6,435		5,904
Free-standing derivatives not designated as hedging instrument | Futures contracts
Derivatives, Fair Value [Line Items]
Derivative, notional amount	[3]	2,240,000		2,110,000
Derivative assets	[1],[3]	0		0
Derivative liabilities	[2],[3]	0		0
Free-standing derivatives not designated as hedging instrument | Total trading account assets and liabilities
Derivatives, Fair Value [Line Items]
Derivative assets	[1]	749,317		336,339
Derivative liabilities	[2]	191,182		118,559
Free-standing derivatives not designated as hedging instrument | Interest rate contracts for customers
Derivatives, Fair Value [Line Items]
Derivative, notional amount		40,169,859		35,503,973
Derivative assets	[1]	711,389		313,573
Derivative liabilities	[2]	155,542		97,881
Free-standing derivatives not designated as hedging instrument | Foreign exchange contracts for customers
Derivatives, Fair Value [Line Items]
Derivative, notional amount		1,400,345		1,039,507
Derivative assets	[1]	37,928		22,766
Derivative liabilities	[2]	$ 35,640		$ 20,678

[1] Derivative assets, except for trading account assets that are recorded as a component of trading account assets on the Company's Unaudited Condensed Consolidated Balance Sheets, are recorded in other assets on the Company’s Unaudited Condensed Consolidated Balance Sheets.

[2] Derivative liabilities are recorded in accrued expenses and other liabilities on the Company’s Unaudited Condensed Consolidated Balance Sheets.

[3] Changes in fair value are cash settled daily; therefore, there is no ending balance at any given reporting period.