Fair Value Measurement and Fair Value of Financial Instruments (Financial Assets and Liabilities Measurement on Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Jan. 01, 2018	Dec. 31, 2017
Investment securities available-for-sale
Available-for-sale debt securities, Fair Value	$ 2,741,847
Available-for-sale debt and equity, Fair Value			$ 3,016,752
Equity Securities with readily determinable fair value		$ 31,900
Derivative
Derivative assets - Fair value	107,816		67,077
Derivative asset, net	62,670		38,391
Derivative liabilities - Fair Value	118,305		75,838
Derivative liability, net	79,903		44,496
U.S. Treasury securities
Investment securities available-for-sale
Available-for-sale debt securities, Fair Value	564,815		640,280
U.S. government agency and U.S. government sponsored enterprise debt securities
Investment securities available-for-sale
Available-for-sale debt securities, Fair Value	217,173		203,392
U.S. government agency and U.S. government sponsored enterprise mortgage-backed securities - Commercial mortgage-backed securities
Investment securities available-for-sale
Available-for-sale debt securities, Fair Value	408,603		318,957
U.S. government agency and U.S. government sponsored enterprise mortgage-backed securities - Residential mortgage-backed securities
Investment securities available-for-sale
Available-for-sale debt securities, Fair Value	946,693		1,190,271
Municipal securities
Investment securities available-for-sale
Available-for-sale debt securities, Fair Value	82,020		99,982
Commercial mortgage-backed securities | Investment grade
Investment securities available-for-sale
Available-for-sale debt securities, Fair Value	26,052
Residential mortgage-backed securities | Investment grade
Investment securities available-for-sale
Available-for-sale debt securities, Fair Value	9,931		9,117
Corporate debt securities | Investment grade
Investment securities available-for-sale
Available-for-sale debt securities, Fair Value	10,869		37,003
Foreign bonds | Investment grade
Investment securities available-for-sale
Available-for-sale debt securities, Fair Value	463,048		486,408
Asset-backed securities | Investment grade
Investment securities available-for-sale
Available-for-sale debt securities, Fair Value	12,643
Other securities
Investment securities available-for-sale
Other securities, Fair Value			31,342
Fair Value, Measurements, Recurring
Investment securities available-for-sale
Available-for-sale debt securities, Fair Value	2,741,847
Available-for-sale debt and equity, Fair Value			3,016,752
Equity Securities with readily determinable fair value	31,209
Total investments in tax credit and other investments	31,209
Derivative
Derivative assets - Fair value	107,816		67,077
Derivative asset netting adjustments	(45,146)		(28,686)
Derivative asset, net	62,670		38,391
Derivative liabilities - Fair Value	118,305		75,838
Derivative liability netting adjustment	(38,402)		(31,342)
Derivative liability, net	79,903		44,496
Fair Value, Measurements, Recurring | Interest rate contracts
Derivative
Derivative assets - Fair value	69,818		59,564
Derivative liabilities - Fair Value	75,133		65,660
Fair Value, Measurements, Recurring | Foreign exchange contracts
Derivative
Derivative assets - Fair value	21,624		5,840
Derivative liabilities - Fair Value	19,940		10,170
Fair Value, Measurements, Recurring | Credit contracts
Derivative
Derivative assets - Fair value	1		1
Derivative liabilities - Fair Value	164		8
Fair Value, Measurements, Recurring | Equity contracts
Derivative
Derivative assets - Fair value	1,951		1,672
Fair Value, Measurements, Recurring | Commodity contracts
Derivative
Derivative assets - Fair value	14,422
Derivative liabilities - Fair Value	23,068
Fair Value, Measurements, Recurring | U.S. Treasury securities
Investment securities available-for-sale
Available-for-sale debt securities, Fair Value	564,815		640,280
Fair Value, Measurements, Recurring | U.S. government agency and U.S. government sponsored enterprise debt securities
Investment securities available-for-sale
Available-for-sale debt securities, Fair Value	217,173		203,392
Fair Value, Measurements, Recurring | U.S. government agency and U.S. government sponsored enterprise mortgage-backed securities - Commercial mortgage-backed securities
Investment securities available-for-sale
Available-for-sale debt securities, Fair Value	408,603		318,957
Fair Value, Measurements, Recurring | U.S. government agency and U.S. government sponsored enterprise mortgage-backed securities - Residential mortgage-backed securities
Investment securities available-for-sale
Available-for-sale debt securities, Fair Value	946,693		1,190,271
Fair Value, Measurements, Recurring | Municipal securities
Investment securities available-for-sale
Available-for-sale debt securities, Fair Value	82,020		99,982
Fair Value, Measurements, Recurring | Commercial mortgage-backed securities | Investment grade
Investment securities available-for-sale
Available-for-sale debt securities, Fair Value	26,052
Fair Value, Measurements, Recurring | Residential mortgage-backed securities | Investment grade
Investment securities available-for-sale
Available-for-sale debt securities, Fair Value	9,931		9,117
Fair Value, Measurements, Recurring | Corporate debt securities | Investment grade
Investment securities available-for-sale
Available-for-sale debt securities, Fair Value	10,869		37,003
Fair Value, Measurements, Recurring | Foreign bonds | Investment grade
Investment securities available-for-sale
Available-for-sale debt securities, Fair Value	463,048		486,408
Fair Value, Measurements, Recurring | Asset-backed securities | Investment grade
Investment securities available-for-sale
Available-for-sale debt securities, Fair Value	12,643
Fair Value, Measurements, Recurring | Other securities
Investment securities available-for-sale
Other securities, Fair Value			31,342
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Investment securities available-for-sale
Available-for-sale debt securities, Fair Value	564,815
Available-for-sale debt and equity, Fair Value			661,015
Equity Securities with readily determinable fair value	20,678
Total investments in tax credit and other investments	20,678
Derivative
Derivative assets - Fair value	0		0
Derivative asset netting adjustments	0		0
Derivative asset, net	0		0
Derivative liabilities - Fair Value	0		0
Derivative liability netting adjustment	0		0
Derivative liability, net	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
Derivative liabilities - Fair Value	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. Treasury securities
Investment securities available-for-sale
Available-for-sale debt securities, Fair Value	564,815		640,280
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
Investment securities available-for-sale
Available-for-sale 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
Investment securities available-for-sale
Available-for-sale 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
Investment securities available-for-sale
Available-for-sale debt securities, Fair Value	0		0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Municipal securities
Investment securities available-for-sale
Available-for-sale debt securities, Fair Value	0		0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Commercial mortgage-backed securities | Investment grade
Investment securities available-for-sale
Available-for-sale debt securities, Fair Value	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Residential mortgage-backed securities | Investment grade
Investment securities available-for-sale
Available-for-sale debt securities, Fair Value	0		0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Corporate debt securities | Investment grade
Investment securities available-for-sale
Available-for-sale debt securities, Fair Value	0		0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Foreign bonds | Investment grade
Investment securities available-for-sale
Available-for-sale debt securities, Fair Value	0		0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Asset-backed securities | Investment grade
Investment securities available-for-sale
Available-for-sale debt securities, Fair Value	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Other securities
Investment securities available-for-sale
Other securities, Fair Value			20,735
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Investment securities available-for-sale
Available-for-sale debt securities, Fair Value	2,177,032
Available-for-sale debt and equity, Fair Value			2,355,737
Equity Securities with readily determinable fair value	10,531
Total investments in tax credit and other investments	10,531
Derivative
Derivative assets - Fair value	107,143		66,398
Derivative asset netting adjustments	(45,146)		(28,686)
Derivative asset, net	61,997		37,712
Derivative liabilities - Fair Value	118,305		75,838
Derivative liability netting adjustment	(38,402)		(31,342)
Derivative liability, net	79,903		44,496
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Interest rate contracts
Derivative
Derivative assets - Fair value	69,818		59,564
Derivative liabilities - Fair Value	75,133		65,660
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Foreign exchange contracts
Derivative
Derivative assets - Fair value	21,624		5,840
Derivative liabilities - Fair Value	19,940		10,170
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Credit contracts
Derivative
Derivative assets - Fair value	1		1
Derivative liabilities - Fair Value	164		8
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Equity contracts
Derivative
Derivative assets - Fair value	1,278		993
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Commodity contracts
Derivative
Derivative assets - Fair value	14,422
Derivative liabilities - Fair Value	23,068
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | U.S. Treasury securities
Investment securities available-for-sale
Available-for-sale 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
Investment securities available-for-sale
Available-for-sale debt securities, Fair Value	217,173		203,392
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
Investment securities available-for-sale
Available-for-sale debt securities, Fair Value	408,603		318,957
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
Investment securities available-for-sale
Available-for-sale debt securities, Fair Value	946,693		1,190,271
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Municipal securities
Investment securities available-for-sale
Available-for-sale debt securities, Fair Value	82,020		99,982
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Commercial mortgage-backed securities | Investment grade
Investment securities available-for-sale
Available-for-sale debt securities, Fair Value	26,052
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Residential mortgage-backed securities | Investment grade
Investment securities available-for-sale
Available-for-sale debt securities, Fair Value	9,931		9,117
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Corporate debt securities | Investment grade
Investment securities available-for-sale
Available-for-sale debt securities, Fair Value	10,869		37,003
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Foreign bonds | Investment grade
Investment securities available-for-sale
Available-for-sale debt securities, Fair Value	463,048		486,408
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Asset-backed securities | Investment grade
Investment securities available-for-sale
Available-for-sale debt securities, Fair Value	12,643
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Other securities
Investment securities available-for-sale
Other securities, Fair Value			10,607
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Investment securities available-for-sale
Available-for-sale debt securities, Fair Value	0
Available-for-sale debt and equity, Fair Value			0
Equity Securities with readily determinable fair value	0
Total investments in tax credit and other investments	0
Derivative
Derivative assets - Fair value	673		679
Derivative asset netting adjustments	0		0
Derivative asset, net	673		679
Derivative liabilities - Fair Value	0		0
Derivative liability netting adjustment	0		0
Derivative liability, net	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	673		679
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Commodity contracts
Derivative
Derivative assets - Fair value	0
Derivative liabilities - Fair Value	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | U.S. Treasury securities
Investment securities available-for-sale
Available-for-sale 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
Investment securities available-for-sale
Available-for-sale 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
Investment securities available-for-sale
Available-for-sale 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
Investment securities available-for-sale
Available-for-sale debt securities, Fair Value	0		0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Municipal securities
Investment securities available-for-sale
Available-for-sale debt securities, Fair Value	0		0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Commercial mortgage-backed securities | Investment grade
Investment securities available-for-sale
Available-for-sale debt securities, Fair Value	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Residential mortgage-backed securities | Investment grade
Investment securities available-for-sale
Available-for-sale debt securities, Fair Value	0		0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Corporate debt securities | Investment grade
Investment securities available-for-sale
Available-for-sale debt securities, Fair Value	0		0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Foreign bonds | Investment grade
Investment securities available-for-sale
Available-for-sale debt securities, Fair Value	0		0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Asset-backed securities | Investment grade
Investment securities available-for-sale
Available-for-sale debt securities, Fair Value	$ 0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Other securities
Investment securities available-for-sale
Other securities, Fair Value			$ 0