Fair Value Measurements (Details 3) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
ASSETS
Held-to-maturity Securities	$ 430,763	$ 477,507
Held to Maturity, Fair Value, Total	441,834	478,749
Loans, net of allowance for loan losses(b)	5,687,928	5,491,896
LIABILITIES
Federal Home Loan Bank borrowings(c)	50,826	102,080
Customer Repurchase Agreements and other short-term borrowings	140,914	133,958
Junior Subordinated Debenture Owed to Unconsolidated Subsidiary Trust	73,157	73,306
Subordinated Debt	34,624	34,589
Time certificates of deposits(c)
LIABILITIES
Time certificates of deposits(c)	629,071	684,830
Accrued Liabilities, Fair Value Disclosure	631,043	684,370
Federal Home Loan Bank borrowings(c)
LIABILITIES
Federal Home Loan Bank borrowings(c)	50,826	102,080
Accrued Liabilities, Fair Value Disclosure	51,172	102,396
Customer repurchase agreements and other short-term borrowings(c)
LIABILITIES
Customer Repurchase Agreements and other short-term borrowings	140,914	133,958
Accrued Liabilities, Fair Value Disclosure	140,914	133,958
Junior subordinated debentures(d)
LIABILITIES
Junior Subordinated Debenture Owed to Unconsolidated Subsidiary Trust	73,157	73,306
Accrued Liabilities, Fair Value Disclosure	75,993	73,871
Subordinated debentures(c)
LIABILITIES
Subordinated Debt	34,624	34,589
Accrued Liabilities, Fair Value Disclosure	35,222	34,370
Significant Other Observable Inputs (Level 2) \| Time certificates of deposits(c)
LIABILITIES
Accrued Liabilities, Fair Value Disclosure	631,043	684,370
Significant Other Observable Inputs (Level 2) \| Federal Home Loan Bank borrowings(c)
LIABILITIES
Accrued Liabilities, Fair Value Disclosure	51,172	102,396
Significant Other Observable Inputs (Level 2) \| Junior subordinated debentures(d)
LIABILITIES
Accrued Liabilities, Fair Value Disclosure	75,993	73,871
Significant Unobservable Inputs (Level 3) \| Customer repurchase agreements and other short-term borrowings(c)
LIABILITIES
Accrued Liabilities, Fair Value Disclosure	140,914	133,958
Significant Unobservable Inputs (Level 3) \| Subordinated debentures(c)
LIABILITIES
Accrued Liabilities, Fair Value Disclosure	35,222	34,370
U.S. Treasury securities
ASSETS
Held-to-maturity Securities	1,008	1,009
Held to Maturity, Fair Value, Total	1,089	1,064
U.S. Treasury securities \| Significant Other Observable Inputs (Level 2)
ASSETS
Held to Maturity, Fair Value, Total	1,089	1,064
Agency mortgage-backed securities
ASSETS
Held-to-maturity Securities	148,822	167,134
Held to Maturity, Fair Value, Total	155,131	170,375
Agency mortgage-backed securities \| Significant Other Observable Inputs (Level 2)
ASSETS
Held to Maturity, Fair Value, Total	155,131	170,375
Agency collateralized mortgage obligations
ASSETS
Held-to-maturity Securities	246,744	267,348
Held to Maturity, Fair Value, Total	250,260	264,891
Agency collateralized mortgage obligations \| Significant Other Observable Inputs (Level 2)
ASSETS
Held to Maturity, Fair Value, Total	250,260	264,891
State, county, and municipal securities
ASSETS
Held-to-maturity Securities		225
Held to Maturity, Fair Value, Total		227
State, county, and municipal securities \| Significant Other Observable Inputs (Level 2)
ASSETS
Held to Maturity, Fair Value, Total		227
Single issuer trust preferred securities issued by banks
ASSETS
Held-to-maturity Securities	1,500	1,500
Held to Maturity, Fair Value, Total	1,547	1,522
Single issuer trust preferred securities issued by banks \| Significant Other Observable Inputs (Level 2)
ASSETS
Held to Maturity, Fair Value, Total	1,547	1,522
Small Business Administration Pooled Securities [Member]
ASSETS
Held-to-maturity Securities	32,689	35,291
Held to Maturity, Fair Value, Total	33,807	35,664
Small Business Administration Pooled Securities [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1)
ASSETS
Held to Maturity, Fair Value, Total	0	0
Small Business Administration Pooled Securities [Member] \| Significant Other Observable Inputs (Level 2)
ASSETS
Held to Maturity, Fair Value, Total	33,807	35,664
Small Business Administration Pooled Securities [Member] \| Significant Unobservable Inputs (Level 3)
ASSETS
Held to Maturity, Fair Value, Total	0	0
Corporate debt securities
ASSETS
Held-to-maturity Securities		5,000
Held to Maturity, Fair Value, Total		5,006
Corporate debt securities \| Significant Other Observable Inputs (Level 2)
ASSETS
Held to Maturity, Fair Value, Total		5,006
Loans, net of allowance for loan losses(b)
ASSETS
Loans, net of allowance for loan losses(b)	5,684,872	5,487,298
Loans Receivable, Fair Value Disclosure	5,622,922	5,417,425
Loans, net of allowance for loan losses(b) \| Significant Unobservable Inputs (Level 3)
ASSETS
Loans Receivable, Fair Value Disclosure	$ 5,622,922	$ 5,417,425

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Amount of borrowings as of the balance sheet date from the Federal Home Loan Bank, which are primarily used to cover shortages in the required reserve balance and liquidity shortages.

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Amount after other than temporary impairment (OTTI) accretion, of investments in debt securities classified as held-to-maturity.

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Including the current and noncurrent portions, the carrying value of junior subordinated long-term debt owed to unconsolidated subsidiary trusts as of the balance sheet date. Such debt places a lender in a lien position behind debt having a higher priority of repayment in liquidation of the entity's assets and was initially scheduled to be repaid after one year or beyond the normal operating cycle if longer.

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Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements and loans held for sale.

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Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

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