Fair Value Measurement and Fair Value of Financial Instruments (Financial Assets and Liabilities Measurement on Recurring Basis) (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Available-for-sale debt securities
AFS debt securities, Fair Value	$ 4,539,160	$ 3,317,214
Equity Securities, FV-NI and with Readily Determinable Fair Value [Abstract]
Total investments in tax credit and other investments	254,512	254,140
Derivative
Derivative assets - Fair value	708,610	330,316
Derivative asset, after netting	598,914	204,997
Derivative liabilities - Fair value	506,019	256,528
Derivative liability, after netting	303,888	96,729
U.S. Treasury securities
Available-for-sale debt securities
AFS debt securities, Fair Value	50,998	176,422
U.S. government agency and U.S. government-sponsored enterprise debt securities
Available-for-sale debt securities
AFS debt securities, Fair Value	727,062	581,245
U.S. government agency and U.S. government-sponsored enterprise mortgage-backed securities - Commercial mortgage-backed securities
Available-for-sale debt securities
AFS debt securities, Fair Value	967,109	603,471
U.S. government agency and U.S. government-sponsored enterprise mortgage-backed securities - Residential mortgage-backed securities
Available-for-sale debt securities
AFS debt securities, Fair Value	1,238,009	1,003,897
Municipal securities
Available-for-sale debt securities
AFS debt securities, Fair Value	333,275	102,302
Non-agency commercial mortgage-backed securities
Available-for-sale debt securities
AFS debt securities, Fair Value	214,676	88,550
Non-agency residential mortgage-backed securities
Available-for-sale debt securities
AFS debt securities, Fair Value	277,613	46,548
Corporate debt securities
Available-for-sale debt securities
AFS debt securities, Fair Value	251,177	11,149
Foreign government bonds
Available-for-sale debt securities
AFS debt securities, Fair Value	132,671	354,172
Asset-backed securities
Available-for-sale debt securities
AFS debt securities, Fair Value	63,148	64,752
Collateralized loan obligations (“CLOs”)
Available-for-sale debt securities
AFS debt securities, Fair Value	283,422	284,706
Fair Value, Measurements, Recurring
Available-for-sale debt securities
AFS debt securities, Fair Value	4,539,160	3,317,214
Equity Securities, FV-NI and with Readily Determinable Fair Value [Abstract]
Equity securities	31,279	31,673
Total investments in tax credit and other investments	31,279	31,673
Derivative
Derivative assets - Fair value	708,610	330,316
Netting adjustments	(109,696)	(125,319)
Derivative asset, after netting	598,914	204,997
Derivative liabilities - Fair value	506,019	256,528
Netting adjustments	(202,131)	(159,799)
Derivative liability, after netting	303,888	96,729
Fair Value, Measurements, Recurring \| Interest rate contracts
Derivative
Derivative assets - Fair value	566,635	192,883
Derivative liabilities - Fair value	372,057	127,317
Fair Value, Measurements, Recurring \| Foreign exchange contracts
Derivative
Derivative assets - Fair value	19,134	54,637
Derivative liabilities - Fair value	14,782	48,610
Fair Value, Measurements, Recurring \| Credit contracts
Derivative
Derivative assets - Fair value	47	2
Derivative liabilities - Fair value	307	84
Fair Value, Measurements, Recurring \| Equity contracts
Derivative
Derivative assets - Fair value	12,765	1,414
Fair Value, Measurements, Recurring \| Commodity contracts
Derivative
Derivative assets - Fair value	110,029	81,380
Derivative liabilities - Fair value	118,873	80,517
Fair Value, Measurements, Recurring \| U.S. Treasury securities
Available-for-sale debt securities
AFS debt securities, Fair Value	50,998	176,422
Fair Value, Measurements, Recurring \| U.S. government agency and U.S. government-sponsored enterprise debt securities
Available-for-sale debt securities
AFS debt securities, Fair Value	727,062	581,245
Fair Value, Measurements, Recurring \| U.S. government agency and U.S. government-sponsored enterprise mortgage-backed securities - Commercial mortgage-backed securities
Available-for-sale debt securities
AFS debt securities, Fair Value	967,109	603,471
Fair Value, Measurements, Recurring \| U.S. government agency and U.S. government-sponsored enterprise mortgage-backed securities - Residential mortgage-backed securities
Available-for-sale debt securities
AFS debt securities, Fair Value	1,238,009	1,003,897
Fair Value, Measurements, Recurring \| Municipal securities
Available-for-sale debt securities
AFS debt securities, Fair Value	333,275	102,302
Fair Value, Measurements, Recurring \| Non-agency commercial mortgage-backed securities
Available-for-sale debt securities
AFS debt securities, Fair Value	214,676	88,550
Fair Value, Measurements, Recurring \| Non-agency residential mortgage-backed securities
Available-for-sale debt securities
AFS debt securities, Fair Value	277,613	46,548
Fair Value, Measurements, Recurring \| Corporate debt securities
Available-for-sale debt securities
AFS debt securities, Fair Value	251,177	11,149
Fair Value, Measurements, Recurring \| Foreign government bonds
Available-for-sale debt securities
AFS debt securities, Fair Value	132,671	354,172
Fair Value, Measurements, Recurring \| Asset-backed securities
Available-for-sale debt securities
AFS debt securities, Fair Value	63,148	64,752
Fair Value, Measurements, Recurring \| Collateralized loan obligations (“CLOs”)
Available-for-sale debt securities
AFS debt securities, Fair Value	283,422	284,706
Fair Value, Measurements, Recurring \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Available-for-sale debt securities
AFS debt securities, Fair Value	50,998	176,422
Equity Securities, FV-NI and with Readily Determinable Fair Value [Abstract]
Equity securities	22,538	21,746
Total investments in tax credit and other investments	22,538	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
Available-for-sale debt securities
AFS debt securities, Fair Value	50,998	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
Available-for-sale debt securities
AFS debt securities, Fair Value	0	0
Fair Value, Measurements, Recurring \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| U.S. government agency and U.S. government-sponsored enterprise mortgage-backed securities - Commercial mortgage-backed securities
Available-for-sale debt securities
AFS debt securities, Fair Value	0	0
Fair Value, Measurements, Recurring \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| U.S. government agency and U.S. government-sponsored enterprise mortgage-backed securities - Residential mortgage-backed securities
Available-for-sale debt securities
AFS debt securities, Fair Value	0	0
Fair Value, Measurements, Recurring \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| Municipal securities
Available-for-sale debt securities
AFS debt securities, Fair Value	0	0
Fair Value, Measurements, Recurring \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| Non-agency commercial mortgage-backed securities
Available-for-sale debt securities
AFS debt securities, Fair Value	0	0
Fair Value, Measurements, Recurring \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| Non-agency residential mortgage-backed securities
Available-for-sale debt securities
AFS debt securities, Fair Value	0	0
Fair Value, Measurements, Recurring \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| Corporate debt securities
Available-for-sale debt securities
AFS debt securities, Fair Value	0	0
Fair Value, Measurements, Recurring \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| Foreign government bonds
Available-for-sale debt securities
AFS debt securities, Fair Value	0	0
Fair Value, Measurements, Recurring \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| Asset-backed securities
Available-for-sale debt securities
AFS debt securities, Fair Value	0	0
Fair Value, Measurements, Recurring \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| Collateralized loan obligations (“CLOs”)
Available-for-sale debt securities
AFS debt securities, Fair Value	0	0
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2)
Available-for-sale debt securities
AFS debt securities, Fair Value	4,488,162	3,140,792
Equity Securities, FV-NI and with Readily Determinable Fair Value [Abstract]
Equity securities	8,741	9,927
Total investments in tax credit and other investments	8,741	9,927
Derivative
Derivative assets - Fair value	708,300	329,895
Netting adjustments	(109,696)	(125,319)
Derivative asset, after netting	598,604	204,576
Derivative liabilities - Fair value	506,019	256,528
Netting adjustments	(202,131)	(159,799)
Derivative liability, after netting	303,888	96,729
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2) \| Interest rate contracts
Derivative
Derivative assets - Fair value	566,635	192,883
Derivative liabilities - Fair value	372,057	127,317
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2) \| Foreign exchange contracts
Derivative
Derivative assets - Fair value	19,134	54,637
Derivative liabilities - Fair value	14,782	48,610
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2) \| Credit contracts
Derivative
Derivative assets - Fair value	47	2
Derivative liabilities - Fair value	307	84
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2) \| Equity contracts
Derivative
Derivative assets - Fair value	12,455	993
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2) \| Commodity contracts
Derivative
Derivative assets - Fair value	110,029	81,380
Derivative liabilities - Fair value	118,873	80,517
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2) \| U.S. Treasury securities
Available-for-sale debt securities
AFS debt securities, 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
Available-for-sale debt securities
AFS debt securities, Fair Value	727,062	581,245
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2) \| U.S. government agency and U.S. government-sponsored enterprise mortgage-backed securities - Commercial mortgage-backed securities
Available-for-sale debt securities
AFS debt securities, Fair Value	967,109	603,471
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2) \| U.S. government agency and U.S. government-sponsored enterprise mortgage-backed securities - Residential mortgage-backed securities
Available-for-sale debt securities
AFS debt securities, Fair Value	1,238,009	1,003,897
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2) \| Municipal securities
Available-for-sale debt securities
AFS debt securities, Fair Value	333,275	102,302
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2) \| Non-agency commercial mortgage-backed securities
Available-for-sale debt securities
AFS debt securities, Fair Value	214,676	88,550
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2) \| Non-agency residential mortgage-backed securities
Available-for-sale debt securities
AFS debt securities, Fair Value	277,613	46,548
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2) \| Corporate debt securities
Available-for-sale debt securities
AFS debt securities, Fair Value	251,177	11,149
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2) \| Foreign government bonds
Available-for-sale debt securities
AFS debt securities, Fair Value	132,671	354,172
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2) \| Asset-backed securities
Available-for-sale debt securities
AFS debt securities, Fair Value	63,148	64,752
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2) \| Collateralized loan obligations (“CLOs”)
Available-for-sale debt securities
AFS debt securities, Fair Value	283,422	284,706
Fair Value, Measurements, Recurring \| Significant Unobservable Inputs (Level 3)
Available-for-sale debt securities
AFS debt securities, Fair Value	0	0
Equity Securities, FV-NI and with Readily Determinable Fair Value [Abstract]
Equity securities	0	0
Total investments in tax credit and other investments	0	0
Derivative
Derivative assets - Fair value	310	421
Netting adjustments	0	0
Derivative asset, after netting	310	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	310	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
Available-for-sale debt securities
AFS debt securities, 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
Available-for-sale debt securities
AFS debt securities, Fair Value	0	0
Fair Value, Measurements, Recurring \| Significant Unobservable Inputs (Level 3) \| U.S. government agency and U.S. government-sponsored enterprise mortgage-backed securities - Commercial mortgage-backed securities
Available-for-sale debt securities
AFS debt securities, Fair Value	0	0
Fair Value, Measurements, Recurring \| Significant Unobservable Inputs (Level 3) \| U.S. government agency and U.S. government-sponsored enterprise mortgage-backed securities - Residential mortgage-backed securities
Available-for-sale debt securities
AFS debt securities, Fair Value	0	0
Fair Value, Measurements, Recurring \| Significant Unobservable Inputs (Level 3) \| Municipal securities
Available-for-sale debt securities
AFS debt securities, Fair Value	0	0
Fair Value, Measurements, Recurring \| Significant Unobservable Inputs (Level 3) \| Non-agency commercial mortgage-backed securities
Available-for-sale debt securities
AFS debt securities, Fair Value	0	0
Fair Value, Measurements, Recurring \| Significant Unobservable Inputs (Level 3) \| Non-agency residential mortgage-backed securities
Available-for-sale debt securities
AFS debt securities, Fair Value	0	0
Fair Value, Measurements, Recurring \| Significant Unobservable Inputs (Level 3) \| Corporate debt securities
Available-for-sale debt securities
AFS debt securities, Fair Value	0	0
Fair Value, Measurements, Recurring \| Significant Unobservable Inputs (Level 3) \| Foreign government bonds
Available-for-sale debt securities
AFS debt securities, Fair Value	0	0
Fair Value, Measurements, Recurring \| Significant Unobservable Inputs (Level 3) \| Asset-backed securities
Available-for-sale debt securities
AFS debt securities, Fair Value	0	0
Fair Value, Measurements, Recurring \| Significant Unobservable Inputs (Level 3) \| Collateralized loan obligations (“CLOs”)
Available-for-sale debt securities
AFS debt securities, Fair Value	$ 0	$ 0

Fair Value Measurement and Fair Value of Financial Instruments (Financial Assets and Liabilities Measurement on Recurring Basis) (Details) - USD ($)
$ in Thousands