Fair Value Measurement and Fair Value of Financial Instruments (Financial Assets and Liabilities Measurement on Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Debt securities available-for-sale
Fair Value	$ 5,544,658	$ 3,317,214
Investments in tax credit and other investments, net	266,525	254,140
Derivative
Derivative assets - Fair value	602,754	330,316
Derivative asset, after netting	501,242	204,997
Derivative liabilities - Fair Value	424,828	256,528
Derivative liability, after netting	240,131	96,729
U.S. Treasury securities
Debt securities available-for-sale
Fair Value	50,761	176,422
U.S. government agency and U.S. government-sponsored enterprise debt securities
Debt securities available-for-sale
Fair Value	814,319	581,245
US government agencies And U.S. government-sponsored enterprise mortgage-backed securities - Commercial mortgage-backed securities
Debt securities available-for-sale
Fair Value	1,153,770	603,471
US government agencies And U.S. government-sponsored enterprise mortgage-backed securities - Residential mortgage-backed securities
Debt securities available-for-sale
Fair Value	1,660,894	1,003,897
Municipal securities
Debt securities available-for-sale
Fair Value	396,073	102,302
Non-agency commercial mortgage-backed Securities
Debt securities available-for-sale
Fair Value	239,842	88,550
Non-agency residential mortgage-backed Securities
Debt securities available-for-sale
Fair Value	289,775	46,548
Corporate debt securities
Debt securities available-for-sale
Fair Value	405,968	11,149
Asset-backed securities
Debt securities available-for-sale
Fair Value	63,231	64,752
Collateralized loan obligations (“CLOs”)
Debt securities available-for-sale
Fair Value	287,494	284,706
Fair Value, Measurements, Recurring
Debt securities available-for-sale
Fair Value	5,544,658	3,317,214
Equity Securities with readily determinable fair value	31,272	31,673
Investments in tax credit and other investments, net	31,272	31,673
Derivative
Derivative assets - Fair value	602,754	330,316
Netting adjustments	(101,512)	(125,319)
Derivative asset, after netting	501,242	204,997
Derivative liabilities - Fair Value	424,828	256,528
Netting adjustments	(184,697)	(159,799)
Derivative liability, after netting	240,131	96,729
Fair Value, Measurements, Recurring | Interest rate contracts
Derivative
Derivative assets - Fair value	489,132	192,883
Derivative liabilities - Fair Value	317,698	127,317
Fair Value, Measurements, Recurring | Foreign exchange contracts
Derivative
Derivative assets - Fair value	30,300	54,637
Derivative liabilities - Fair Value	22,759	48,610
Fair Value, Measurements, Recurring | Credit contracts
Derivative
Derivative assets - Fair value	13	2
Derivative liabilities - Fair Value	206	84
Fair Value, Measurements, Recurring | Equity contracts
Derivative
Derivative assets - Fair value	858	1,414
Fair Value, Measurements, Recurring | Commodity contracts
Derivative
Derivative assets - Fair value	82,451	81,380
Derivative liabilities - Fair Value	84,165	80,517
Fair Value, Measurements, Recurring | U.S. Treasury securities
Debt securities available-for-sale
Fair Value	50,761	176,422
Fair Value, Measurements, Recurring | U.S. government agency and U.S. government-sponsored enterprise debt securities
Debt securities available-for-sale
Fair Value	814,319	581,245
Fair Value, Measurements, Recurring | US government agencies And U.S. government-sponsored enterprise mortgage-backed securities - Commercial mortgage-backed securities
Debt securities available-for-sale
Fair Value	1,153,770	603,471
Fair Value, Measurements, Recurring | US government agencies And U.S. government-sponsored enterprise mortgage-backed securities - Residential mortgage-backed securities
Debt securities available-for-sale
Fair Value	1,660,894	1,003,897
Fair Value, Measurements, Recurring | Municipal securities
Debt securities available-for-sale
Fair Value	396,073	102,302
Fair Value, Measurements, Recurring | Non-agency commercial mortgage-backed Securities
Debt securities available-for-sale
Fair Value	239,842	88,550
Fair Value, Measurements, Recurring | Non-agency residential mortgage-backed Securities
Debt securities available-for-sale
Fair Value	289,775	46,548
Fair Value, Measurements, Recurring | Corporate debt securities
Debt securities available-for-sale
Fair Value	405,968	11,149
Fair Value, Measurements, Recurring | Asset-backed securities
Debt securities available-for-sale
Fair Value	63,231	64,752
Fair Value, Measurements, Recurring | Collateralized loan obligations (“CLOs”)
Debt securities available-for-sale
Fair Value	287,494	284,706
Fair Value, Measurements, Recurring | Foreign Government Debt
Debt securities available-for-sale
Fair Value	182,531	354,172
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Debt securities available-for-sale
Fair Value	50,761	176,422
Equity Securities with readily determinable fair value	22,548	21,746
Investments in tax credit and other investments, net	22,548	21,746
Derivative
Derivative assets - Fair value	0	0
Netting adjustments	0	0
Derivative asset, after netting	0	0
Derivative liabilities - Fair Value	0	0
Netting adjustments	0	0
Derivative liability, after netting	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Interest rate contracts
Derivative
Derivative assets - Fair value	0	0
Derivative liabilities - Fair Value	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Foreign exchange contracts
Derivative
Derivative assets - Fair value	0	0
Derivative liabilities - Fair Value	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Credit contracts
Derivative
Derivative assets - Fair value	0	0
Derivative liabilities - Fair Value	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Equity contracts
Derivative
Derivative assets - Fair value	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Commodity contracts
Derivative
Derivative assets - Fair value	0	0
Derivative liabilities - Fair Value	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. Treasury securities
Debt securities available-for-sale
Fair Value	50,761	176,422
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. government agency and U.S. government-sponsored enterprise debt securities
Debt securities available-for-sale
Fair Value	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | US government agencies And U.S. government-sponsored enterprise mortgage-backed securities - Commercial mortgage-backed securities
Debt securities available-for-sale
Fair Value	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | US government agencies And U.S. government-sponsored enterprise mortgage-backed securities - Residential mortgage-backed securities
Debt securities available-for-sale
Fair Value	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Municipal securities
Debt securities available-for-sale
Fair Value	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Non-agency commercial mortgage-backed Securities
Debt securities available-for-sale
Fair Value	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Non-agency residential mortgage-backed Securities
Debt securities available-for-sale
Fair Value	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Corporate debt securities
Debt securities available-for-sale
Fair Value	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Asset-backed securities
Debt securities available-for-sale
Fair Value	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Collateralized loan obligations (“CLOs”)
Debt securities available-for-sale
Fair Value	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Foreign Government Debt
Debt securities available-for-sale
Fair Value	0	0
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Debt securities available-for-sale
Fair Value	5,493,897	3,140,792
Equity Securities with readily determinable fair value	8,724	9,927
Investments in tax credit and other investments, net	8,724	9,927
Derivative
Derivative assets - Fair value	602,481	329,895
Netting adjustments	(101,512)	(125,319)
Derivative asset, after netting	500,969	204,576
Derivative liabilities - Fair Value	424,828	256,528
Netting adjustments	(184,697)	(159,799)
Derivative liability, after netting	240,131	96,729
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Interest rate contracts
Derivative
Derivative assets - Fair value	489,132	192,883
Derivative liabilities - Fair Value	317,698	127,317
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Foreign exchange contracts
Derivative
Derivative assets - Fair value	30,300	54,637
Derivative liabilities - Fair Value	22,759	48,610
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Credit contracts
Derivative
Derivative assets - Fair value	13	2
Derivative liabilities - Fair Value	206	84
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Equity contracts
Derivative
Derivative assets - Fair value	585	993
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Commodity contracts
Derivative
Derivative assets - Fair value	82,451	81,380
Derivative liabilities - Fair Value	84,165	80,517
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | U.S. Treasury securities
Debt securities available-for-sale
Fair Value	0	0
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | U.S. government agency and U.S. government-sponsored enterprise debt securities
Debt securities available-for-sale
Fair Value	814,319	581,245
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | US government agencies And U.S. government-sponsored enterprise mortgage-backed securities - Commercial mortgage-backed securities
Debt securities available-for-sale
Fair Value	1,153,770	603,471
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | US government agencies And U.S. government-sponsored enterprise mortgage-backed securities - Residential mortgage-backed securities
Debt securities available-for-sale
Fair Value	1,660,894	1,003,897
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Municipal securities
Debt securities available-for-sale
Fair Value	396,073	102,302
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Non-agency commercial mortgage-backed Securities
Debt securities available-for-sale
Fair Value	239,842	88,550
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Non-agency residential mortgage-backed Securities
Debt securities available-for-sale
Fair Value	289,775	46,548
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Corporate debt securities
Debt securities available-for-sale
Fair Value	405,968	11,149
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Asset-backed securities
Debt securities available-for-sale
Fair Value	63,231	64,752
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Collateralized loan obligations (“CLOs”)
Debt securities available-for-sale
Fair Value	287,494	284,706
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Foreign Government Debt
Debt securities available-for-sale
Fair Value	182,531	354,172
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Debt securities available-for-sale
Fair Value	0	0
Equity Securities with readily determinable fair value	0	0
Investments in tax credit and other investments, net	0	0
Derivative
Derivative assets - Fair value	273	421
Netting adjustments	0	0
Derivative asset, after netting	273	421
Derivative liabilities - Fair Value	0	0
Netting adjustments	0	0
Derivative liability, after netting	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Interest rate contracts
Derivative
Derivative assets - Fair value	0	0
Derivative liabilities - Fair Value	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Foreign exchange contracts
Derivative
Derivative assets - Fair value	0	0
Derivative liabilities - Fair Value	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Credit contracts
Derivative
Derivative assets - Fair value	0	0
Derivative liabilities - Fair Value	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Equity contracts
Derivative
Derivative assets - Fair value	273	421
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Commodity contracts
Derivative
Derivative assets - Fair value	0	0
Derivative liabilities - Fair Value	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | U.S. Treasury securities
Debt securities available-for-sale
Fair Value	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | U.S. government agency and U.S. government-sponsored enterprise debt securities
Debt securities available-for-sale
Fair Value	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | US government agencies And U.S. government-sponsored enterprise mortgage-backed securities - Commercial mortgage-backed securities
Debt securities available-for-sale
Fair Value	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | US government agencies And U.S. government-sponsored enterprise mortgage-backed securities - Residential mortgage-backed securities
Debt securities available-for-sale
Fair Value	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Municipal securities
Debt securities available-for-sale
Fair Value	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Non-agency commercial mortgage-backed Securities
Debt securities available-for-sale
Fair Value	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Non-agency residential mortgage-backed Securities
Debt securities available-for-sale
Fair Value	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Corporate debt securities
Debt securities available-for-sale
Fair Value	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Asset-backed securities
Debt securities available-for-sale
Fair Value	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Collateralized loan obligations (“CLOs”)
Debt securities available-for-sale
Fair Value	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Foreign Government Debt
Debt securities available-for-sale
Fair Value	$ 0	$ 0