Fair Value Measurement and Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Investment securities available-for-sale
Available-for-sale investment securities	$ 2,962,034	$ 3,335,795
Derivative
Derivative assets	69,809	83,780
Derivative liabilities	(74,356)	(82,323)
U.S. Treasury securities
Investment securities available-for-sale
Available-for-sale investment securities	700,860	720,479
U.S. government agency and U.S. government sponsored enterprise debt securities
Investment securities available-for-sale
Available-for-sale investment securities	180,863	274,866
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	264,522	266,799
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	1,179,755	1,258,747
Municipal securities
Investment securities available-for-sale
Available-for-sale investment securities	147,069	147,654
Non-agency residential mortgage-backed securities | Investment grade
Investment securities available-for-sale
Available-for-sale investment securities	10,730	11,477
Corporate debt securities | Investment grade
Investment securities available-for-sale
Available-for-sale investment securities	2,254	222,377
Corporate debt securities | Non-investment grade
Investment securities available-for-sale
Available-for-sale investment securities	9,184	9,173
Foreign bonds | Investment grade
Investment securities available-for-sale
Available-for-sale investment securities	425,868	383,894
Other securities
Investment securities available-for-sale
Available-for-sale investment securities	40,929	40,329
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Investment securities available-for-sale
Available-for-sale investment securities	731,935	751,470
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	700,860	720,479
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	31,075	30,991
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Investment securities available-for-sale
Available-for-sale investment securities	2,230,099	2,584,325
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Interest rate swaps and options
Derivative
Derivative assets	61,586	67,578
Derivative liabilities	(60,204)	(65,131)
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Foreign exchange contracts
Derivative
Derivative assets	8,220	11,874
Derivative liabilities	(7,357)	(11,213)
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | RPAs
Derivative
Derivative assets	3	3
Derivative liabilities	(2)	(3)
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Interest rate swaps on certificates of deposit
Derivative
Derivative liabilities	(6,793)	(5,976)
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Foreign currency forward contracts
Derivative
Derivative assets		4,325
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	180,863	274,866
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	264,522	266,799
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	1,179,755	1,258,747
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Municipal securities
Investment securities available-for-sale
Available-for-sale investment securities	147,069	147,654
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	10,730	11,477
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	2,254	222,377
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Corporate debt securities | Non-investment grade
Investment securities available-for-sale
Available-for-sale investment securities	9,184	9,173
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Foreign bonds | Investment grade
Investment securities available-for-sale
Available-for-sale investment securities	425,868	383,894
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Other securities
Investment securities available-for-sale
Available-for-sale investment securities	9,854	9,338
Fair Value, Measurements, Recurring | Estimated Fair Value
Investment securities available-for-sale
Available-for-sale investment securities	2,962,034	3,335,795
Fair Value, Measurements, Recurring | Estimated Fair Value | Interest rate swaps and options
Derivative
Derivative assets	61,586	67,578
Derivative liabilities	(60,204)	(65,131)
Fair Value, Measurements, Recurring | Estimated Fair Value | Foreign exchange contracts
Derivative
Derivative assets	8,220	11,874
Derivative liabilities	(7,357)	(11,213)
Fair Value, Measurements, Recurring | Estimated Fair Value | RPAs
Derivative
Derivative assets	3	3
Derivative liabilities	(2)	(3)
Fair Value, Measurements, Recurring | Estimated Fair Value | Interest rate swaps on certificates of deposit
Derivative
Derivative liabilities	(6,793)	(5,976)
Fair Value, Measurements, Recurring | Estimated Fair Value | Foreign currency forward contracts
Derivative
Derivative assets		4,325
Fair Value, Measurements, Recurring | Estimated Fair Value | U.S. Treasury securities
Investment securities available-for-sale
Available-for-sale investment securities	700,860	720,479
Fair Value, Measurements, Recurring | Estimated Fair Value | U.S. government agency and U.S. government sponsored enterprise debt securities
Investment securities available-for-sale
Available-for-sale investment securities	180,863	274,866
Fair Value, Measurements, Recurring | Estimated Fair Value | 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	264,522	266,799
Fair Value, Measurements, Recurring | Estimated Fair Value | 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	1,179,755	1,258,747
Fair Value, Measurements, Recurring | Estimated Fair Value | Municipal securities
Investment securities available-for-sale
Available-for-sale investment securities	147,069	147,654
Fair Value, Measurements, Recurring | Estimated Fair Value | Non-agency residential mortgage-backed securities | Investment grade
Investment securities available-for-sale
Available-for-sale investment securities	10,730	11,477
Fair Value, Measurements, Recurring | Estimated Fair Value | Corporate debt securities | Investment grade
Investment securities available-for-sale
Available-for-sale investment securities	2,254	222,377
Fair Value, Measurements, Recurring | Estimated Fair Value | Corporate debt securities | Non-investment grade
Investment securities available-for-sale
Available-for-sale investment securities	9,184	9,173
Fair Value, Measurements, Recurring | Estimated Fair Value | Foreign bonds | Investment grade
Investment securities available-for-sale
Available-for-sale investment securities	425,868	383,894
Fair Value, Measurements, Recurring | Estimated Fair Value | Other securities
Investment securities available-for-sale
Available-for-sale investment securities	$ 40,929	$ 40,329