Fair Value Measurements Narrative (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities valued by the pricing service	94.00%	94.00%
Researched securities to reconcile the difference	5.00%	5.00%
Corporate debt securities	$ 2,485,585	$ 2,485,585
Significant input, assumed market return to liquidity (years)	5 years
Other real estate owned (OREO)	$ 11,981	$ 11,981	$ 11,099
Minimum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Weighted average annual constant prepayment rate		14.40%
Weighted average discount rate		10.10%
Equity Securities Financial Institution [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, equity securities	21,600	$ 21,600	20,600
Equity Securities, Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, equity securities	901	901
Corporate Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Corporate debt securities	107,241	107,241	96,955
Senior Debt Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Corporate debt securities	18,601	18,601	12,329
Single-issuer Trust Preferred Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Corporate debt securities	39,253	39,253	39,106
Pooled Trust Preferred Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Corporate debt securities	706	706	706
Fair Value, Measurements, Recurring [Member] | Single-issuer Trust Preferred Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Corporate debt securities	39,300	39,300	39,100
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Trust for Benefit of Employees [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other financial assets	16,400	16,400	15,600
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Foreign Exchange Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other financial assets	527	527	547
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Trust for Benefit of Employees [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other financial liabilities	16,400	16,400	15,600
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Foreign Exchange Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other financial liabilities	424	424	331
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Equity Securities Financial Institution [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, equity securities	21,600	21,600	20,600
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Equity Securities, Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, equity securities	901	901	914
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Forward Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other financial assets	3,200	3,200	1,500
Other financial liabilities	868	868	40
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Interest Rate Swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other financial assets	80,900	80,900	33,000
Other financial liabilities	80,900	80,900	33,000
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Financial Institutions Subordinated Debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Corporate debt securities	44,700	44,700	40,800
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Senior Debt Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Corporate debt securities	18,600	18,600	12,300
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Single-issuer Trust Preferred Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Corporate debt securities	36,800	36,800	36,500
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Other Corporate Debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Corporate debt securities	4,000	4,000	4,000
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Single-issuer Trust Preferred Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Corporate debt securities	2,400	2,400	2,600
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Pooled Trust Preferred Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Corporate debt securities	706	706	706
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other real estate owned (OREO)	12,000	12,000	11,100
Other financial assets (MSRs)	$ 36,300	$ 36,300	$ 40,900