Fair Value Measurements Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Equity securities, value test coverage	80.00%
Fair value price difference threshold	5.00%
Estimated Fair Value	$ 2,463,259
Other real estate owned (OREO)	$ 11,099	$ 12,022
Assumed market return to liquidity	5 years
Equity Securities Financial Institution
Available-for-sale securities, equity securities	$ 20,600	41,800
Equity Securities, Miscellaneous
Available-for-sale securities, equity securities	914	5,800
Corporate debt securities
Estimated Fair Value	96,955	98,034
Single-issuer trust preferred securities
Estimated Fair Value	39,106	42,016
Pooled trust preferred securities
Estimated Fair Value	706	4,088
Level 3 | Other Assets
Other real estate owned (OREO)	11,100	12,000
Fair value of servicing asset at amortized value	40,900	42,100
Fair Value, Measurements, Recurring
Other financial assets	50,594	38,987
Other financial liabilities	48,924	38,821
Fair Value, Measurements, Recurring | Single-issuer trust preferred securities
Estimated Fair Value	39,100	42,000
Fair Value, Measurements, Recurring | Level 1
Other financial assets	16,129	17,682
Other financial liabilities	15,914	17,737
Fair Value, Measurements, Recurring | Level 1 | Equity Securities Financial Institution
Available-for-sale securities, equity securities	20,600	41,800
Fair Value, Measurements, Recurring | Level 1 | Equity Securities, Miscellaneous
Available-for-sale securities, equity securities	914	5,800
Fair Value, Measurements, Recurring | Level 2
Other financial assets	34,465	21,305
Other financial liabilities	33,010	21,084
Fair Value, Measurements, Recurring | Level 2 | Financial Institutions Subordinated Debt
Estimated Fair Value	53,100	50,000
Fair Value, Measurements, Recurring | Level 2 | Single-issuer trust preferred securities
Estimated Fair Value	36,500	38,200
Fair Value, Measurements, Recurring | Level 2 | Other Corporate Debt
Estimated Fair Value	4,000	1,900
Fair Value, Measurements, Recurring | Level 3
Other financial assets	0	0
Other financial liabilities	0	0
Fair Value, Measurements, Recurring | Level 3 | Single-issuer trust preferred securities
Estimated Fair Value	2,600	3,800
Fair Value, Measurements, Recurring | Level 3 | Pooled trust preferred securities
Estimated Fair Value	$ 706	4,100
Minimum
Assumptions used to estimate fair value, prepayment speed	11.20%
Assumptions used to estimate fair value, discount rate	9.60%
Trust for Benefit of Employees | Fair Value, Measurements, Recurring | Level 1
Other financial assets	$ 15,600	16,400
Foreign Exchange Contract | Fair Value, Measurements, Recurring | Level 1
Other financial assets	547	1,300
Forward Commitments | Fair Value, Measurements, Recurring | Level 2
Other financial assets	1,500	1,400
Other financial liabilities	40	1,200
Interest Rate Swap | Fair Value, Measurements, Recurring | Level 2
Other financial assets	33,000	19,900
Other financial liabilities	33,000	19,900
Foreign Exchange Contract | Fair Value, Measurements, Recurring | Level 1
Other financial liabilities	331	1,300
Trust for Benefit of Employees | Fair Value, Measurements, Recurring | Level 1
Other financial liabilities	$ 15,600	$ 16,400
Short Term Financial Instruments
Short term borrowings, reprice period	90