Derivatives and Hedging - Derivatives by Balance Sheet Location (Details) - USD ($) $ in Thousands		Mar. 31, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Derivative assets		$ 106,289	$ 93,409
Derivative liabilities		96,522	108,955
Derivatives designated as hedging instrument
Derivatives, Fair Value [Line Items]
Derivative assets	[1]	15,081	19,724
Derivative liabilities	[2]	41,393	21,401
Derivatives designated as hedging instrument | Fair value hedges
Derivatives, Fair Value [Line Items]
Derivative assets	[1]	14,847	19,399
Derivative liabilities	[2]	39,118	16,831
Derivatives designated as hedging instrument | Fair value hedges | Interest rate swap long term debt
Derivatives, Fair Value [Line Items]
Derivative, notional amount		2,223,950	2,223,950
Derivative assets	[1]	14,847	19,399
Derivative liabilities	[2]	39,118	16,831
Derivatives designated as hedging instrument | Cash flow hedges
Derivatives, Fair Value [Line Items]
Derivative assets	[1]	234	325
Derivative liabilities	[2]	2,275	4,570
Derivatives designated as hedging instrument | Cash flow hedges | Interest rate swap commercial loan
Derivatives, Fair Value [Line Items]
Derivative, notional amount		7,900,000	9,075,000
Derivative assets	[1]	160	325
Derivative liabilities	[2]	24	2
Derivatives designated as hedging instrument | Cash flow hedges | Interest rate swap FHLB advances
Derivatives, Fair Value [Line Items]
Derivative, notional amount		120,000	120,000
Derivative liabilities	[2]	2,251	4,424
Derivatives designated as hedging instrument | Cash flow hedges | Foreign exchange contracts
Derivatives, Fair Value [Line Items]
Derivative, notional amount		1,662	3,220
Derivative assets	[1]	74
Derivative liabilities	[2]	0	144
Free-standing derivatives not designated as hedging instrument
Derivatives, Fair Value [Line Items]
Derivative assets	[1]	163,688	188,370
Derivative liabilities	[2]	209,033	186,531
Free-standing derivatives not designated as hedging instrument | Forward contracts related to residential mortgage loans held for sale
Derivatives, Fair Value [Line Items]
Derivative, notional amount		205,500	141,000
Derivative assets	[1]	526	85
Derivative liabilities	[2]	491	130
Free-standing derivatives not designated as hedging instrument | Option contracts related to mortgage servicing rights
Derivatives, Fair Value [Line Items]
Derivative, notional amount		0	40,000
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		143,882	114,184
Derivative assets	[1]	2,609	2,416
Derivative liabilities	[2]	1	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		766,985	810,011
Derivative assets	[1]	34,248	39,791
Free-standing derivatives not designated as hedging instrument | Written equity option related to equity-linked CDs
Derivatives, Fair Value [Line Items]
Derivative, notional amount		677,293	718,428
Derivative liabilities	[2]	30,435	35,562
Free-standing derivatives not designated as hedging instrument | Forward contracts related to commercial loans
Derivatives, Fair Value [Line Items]
Derivative, notional amount		413,847	358,729
Derivative assets	[1]	2,262	291
Derivative liabilities	[2]	787	3,501
Free-standing derivatives not designated as hedging instrument | Spot contracts related to commercial loans
Derivatives, Fair Value [Line Items]
Derivative, notional amount		14,994	83,338
Derivative assets	[1]	24	84
Derivative liabilities	[2]	2	245
Free-standing derivatives not designated as hedging instrument | Equity contracts, swap associated with sale of Visa Inc. Class B shares
Derivatives, Fair Value [Line Items]
Derivative, notional amount		104,729	99,826
Derivative liabilities	[2]	2,618	2,496
Free-standing derivatives not designated as hedging instrument | Futures contracts
Derivatives, Fair Value [Line Items]
Derivative, notional amount	[3]	1,754,000	1,449,000
Free-standing derivatives not designated as hedging instrument | Interest rate contracts for customers
Derivatives, Fair Value [Line Items]
Derivative, notional amount		30,068,194	30,472,359
Derivative assets	[1]	110,694	133,516
Derivative liabilities	[2]	163,060	134,073
Free-standing derivatives not designated as hedging instrument | Foreign exchange contracts for customers
Derivatives, Fair Value [Line Items]
Derivative, notional amount		913,072	514,185
Derivative assets	[1]	13,325	12,149
Derivative liabilities	[2]	11,639	10,524
Free-standing derivatives not designated as hedging instrument | Total trading account assets and liabilities
Derivatives, Fair Value [Line Items]
Derivative assets	[1]	124,019	145,665
Derivative liabilities	[2]	$ 174,699	$ 144,597

[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.