Derivatives - Schedule of Notional Amounts and Estimated Fair Values (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Feb. 28, 2019	Dec. 31, 2018
Derivatives Fair Value [Line Items]
Notional Amount	$ 6,710,773		$ 2,696,100
Fair Value, Other Assets	182,287		11,136
Fair Value, Other Liabilities	24,046		32,350
Cash Flow Hedges
Derivatives Fair Value [Line Items]
Notional Amount		$ 4,000,000
Derivatives Designated as Hedging Instruments \| Cash Flow Hedges
Derivatives Fair Value [Line Items]
Notional Amount	4,650,000		650,000
Fair Value, Other Assets	169,277
Fair Value, Other Liabilities	15,814		23,968
Derivatives Designated as Hedging Instruments \| Cash Flow Hedges \| Commercial Loans \| Interest Rate Swaps
Derivatives Fair Value [Line Items]
Notional Amount	650,000		650,000
Fair Value, Other Liabilities	15,814		23,968
Derivatives Designated as Hedging Instruments \| Cash Flow Hedges \| Commercial Loans \| Interest Rate Collars
Derivatives Fair Value [Line Items]
Notional Amount	4,000,000
Fair Value, Other Assets	169,277
Derivatives Not Designated as Hedging Instruments
Derivatives Fair Value [Line Items]
Notional Amount	2,060,773		2,046,100
Fair Value, Other Assets	13,010		11,136
Fair Value, Other Liabilities	8,232		8,382
Derivatives Not Designated as Hedging Instruments \| Mortgage Loan Held for Sale Interest Rate Lock Commitments
Derivatives Fair Value [Line Items]
Notional Amount	10,320		5,286
Fair Value, Other Assets	145		72
Derivatives Not Designated as Hedging Instruments \| Mortgage Loan Held for Sale Floating Commitments
Derivatives Fair Value [Line Items]
Notional Amount	2,518		14,690
Derivatives Not Designated as Hedging Instruments \| Foreign Exchange Contracts
Derivatives Fair Value [Line Items]
Notional Amount	50,552		46,971
Fair Value, Other Assets	372		698
Fair Value, Other Liabilities	347		683
Derivatives Not Designated as Hedging Instruments \| Commercial Loans \| Interest Rate Swaps
Derivatives Fair Value [Line Items]
Notional Amount	1,127,780		1,155,942
Fair Value, Other Assets	5,672		4,439
Fair Value, Other Liabilities	1,078		1,777
Derivatives Not Designated as Hedging Instruments \| Commercial Loans \| Interest Rate Collars
Derivatives Fair Value [Line Items]
Notional Amount	80,000		80,000
Fair Value, Other Assets	128		96
Fair Value, Other Liabilities	128		96
Derivatives Not Designated as Hedging Instruments \| Commercial Loans \| Interest Rate Caps
Derivatives Fair Value [Line Items]
Notional Amount	112,194		88,430
Fair Value, Other Assets	176		239
Fair Value, Other Liabilities	176		239
Derivatives Not Designated as Hedging Instruments \| Commercial Loans \| Interest Rate Floors
Derivatives Fair Value [Line Items]
Notional Amount	673,340		652,822
Fair Value, Other Assets	6,503		5,587
Fair Value, Other Liabilities	6,503		5,587
Derivatives Not Designated as Hedging Instruments \| Forward Contracts \| Mortgage Loan Forward Sale Commitments
Derivatives Fair Value [Line Items]
Notional Amount	4,069		1,959
Fair Value, Other Assets	$ 14		$ 5

Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 13
-Sentence Column B

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+ References

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-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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