Fair Value Measurement and Fair Value of Financial Instruments (Financial Assets and Liabilities Measurement on Recurring Basis) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Investment securities available-for-sale
Equity securities		$ 31,900
Derivative
Derivative assets	$ 59,831	66,146
Derivative liabilities	86,673	74,935
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Investment securities available-for-sale
Available-for-sale investment securities	651,830	661,015
Equity securities	20,489
Total investments in tax credit and other investments	20,489
Derivative
Derivative assets	0	0
Derivative liabilities	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Interest rate swaps and options
Derivative
Derivative assets	0	0
Derivative liabilities	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Foreign exchange spot and forwards
Derivative
Derivative assets	0	0
Derivative liabilities	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | RPAs
Derivative
Derivative assets	0	0
Derivative liabilities	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Equity warrants
Derivative
Derivative assets	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Commodity options
Derivative
Derivative assets	0
Derivative liabilities	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Interest rate swaps
Derivative
Derivative liabilities	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Foreign exchange forwards
Derivative
Derivative liabilities	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 investment securities	651,830	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 investment securities	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 investment securities	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 investment securities	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 investment securities	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Non-agency residential mortgage-backed securities | Investment grade
Investment securities available-for-sale
Available-for-sale investment securities	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 investment securities	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 investment securities	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Other securities
Investment securities available-for-sale
Available-for-sale investment securities		20,735
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Investment securities available-for-sale
Available-for-sale investment securities	2,159,586	2,355,737
Equity securities	10,498
Total investments in tax credit and other investments	10,498
Derivative
Derivative assets	58,900	65,467
Derivative liabilities	86,673	74,935
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Interest rate swaps and options
Derivative
Derivative assets	51,933	58,633
Derivative liabilities	72,893	57,958
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Foreign exchange spot and forwards
Derivative
Derivative assets	6,087	5,840
Derivative liabilities	4,066	10,170
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | RPAs
Derivative
Derivative assets	1	1
Derivative liabilities	21	8
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Equity warrants
Derivative
Derivative assets	582	993
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Commodity options
Derivative
Derivative assets	297
Derivative liabilities	288
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Interest rate swaps
Derivative
Derivative liabilities	8,251	6,799
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Foreign exchange forwards
Derivative
Derivative liabilities	1,154
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | U.S. Treasury securities
Investment securities available-for-sale
Available-for-sale investment securities	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 investment securities	233,016	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 investment securities	339,834	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 investment securities	989,453	1,190,271
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Municipal securities
Investment securities available-for-sale
Available-for-sale investment securities	74,076	99,982
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Non-agency residential mortgage-backed securities | Investment grade
Investment securities available-for-sale
Available-for-sale investment securities	8,404	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 investment securities	35,858	37,003
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Foreign bonds | Investment grade
Investment securities available-for-sale
Available-for-sale investment securities	478,945	486,408
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Other securities
Investment securities available-for-sale
Available-for-sale investment securities		10,607
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Investment securities available-for-sale
Available-for-sale investment securities	0	0
Equity securities	0
Total investments in tax credit and other investments	0
Derivative
Derivative assets	931	679
Derivative liabilities	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Interest rate swaps and options
Derivative
Derivative assets	0	0
Derivative liabilities	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Foreign exchange spot and forwards
Derivative
Derivative assets	0	0
Derivative liabilities	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | RPAs
Derivative
Derivative assets	0	0
Derivative liabilities	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Equity warrants
Derivative
Derivative assets	931	679
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Commodity options
Derivative
Derivative assets	0
Derivative liabilities	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Interest rate swaps
Derivative
Derivative liabilities	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Foreign exchange forwards
Derivative
Derivative liabilities	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | U.S. Treasury securities
Investment securities available-for-sale
Available-for-sale investment securities	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 investment securities	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 investment securities	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 investment securities	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Municipal securities
Investment securities available-for-sale
Available-for-sale investment securities	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Non-agency residential mortgage-backed securities | Investment grade
Investment securities available-for-sale
Available-for-sale investment securities	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Corporate debt securities | Investment grade
Investment securities available-for-sale
Available-for-sale investment securities	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Foreign bonds | Investment grade
Investment securities available-for-sale
Available-for-sale investment securities	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Other securities
Investment securities available-for-sale
Available-for-sale investment securities		0
Fair Value, Measurements, Recurring | Fair Value Measurements
Investment securities available-for-sale
Available-for-sale investment securities	2,811,416	3,016,752
Equity securities	30,987
Total investments in tax credit and other investments	30,987
Derivative
Derivative assets	59,831	66,146
Derivative liabilities	86,673	74,935
Fair Value, Measurements, Recurring | Fair Value Measurements | Interest rate swaps and options
Derivative
Derivative assets	51,933	58,633
Derivative liabilities	72,893	57,958
Fair Value, Measurements, Recurring | Fair Value Measurements | Foreign exchange spot and forwards
Derivative
Derivative assets	6,087	5,840
Derivative liabilities	4,066	10,170
Fair Value, Measurements, Recurring | Fair Value Measurements | RPAs
Derivative
Derivative assets	1	1
Derivative liabilities	21	8
Fair Value, Measurements, Recurring | Fair Value Measurements | Equity warrants
Derivative
Derivative assets	1,513	1,672
Fair Value, Measurements, Recurring | Fair Value Measurements | Commodity options
Derivative
Derivative assets	297
Derivative liabilities	288
Fair Value, Measurements, Recurring | Fair Value Measurements | Interest rate swaps
Derivative
Derivative liabilities	8,251	6,799
Fair Value, Measurements, Recurring | Fair Value Measurements | Foreign exchange forwards
Derivative
Derivative liabilities	1,154
Fair Value, Measurements, Recurring | Fair Value Measurements | U.S. Treasury securities
Investment securities available-for-sale
Available-for-sale investment securities	651,830	640,280
Fair Value, Measurements, Recurring | Fair Value Measurements | U.S. government agency and U.S. government sponsored enterprise debt securities
Investment securities available-for-sale
Available-for-sale investment securities	233,016	203,392
Fair Value, Measurements, Recurring | Fair Value Measurements | 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 investment securities	339,834	318,957
Fair Value, Measurements, Recurring | Fair Value Measurements | 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 investment securities	989,453	1,190,271
Fair Value, Measurements, Recurring | Fair Value Measurements | Municipal securities
Investment securities available-for-sale
Available-for-sale investment securities	74,076	99,982
Fair Value, Measurements, Recurring | Fair Value Measurements | Non-agency residential mortgage-backed securities | Investment grade
Investment securities available-for-sale
Available-for-sale investment securities	8,404	9,117
Fair Value, Measurements, Recurring | Fair Value Measurements | Corporate debt securities | Investment grade
Investment securities available-for-sale
Available-for-sale investment securities	35,858	37,003
Fair Value, Measurements, Recurring | Fair Value Measurements | Foreign bonds | Investment grade
Investment securities available-for-sale
Available-for-sale investment securities	$ 478,945	486,408
Fair Value, Measurements, Recurring | Fair Value Measurements | Other securities
Investment securities available-for-sale
Available-for-sale investment securities		$ 31,342