Fair Value Measurements (Details 3) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
ASSETS
Held-to-maturity Securities	$ 498,392	$ 487,076
Held to Maturity, Fair Value, Total	499,059	485,650
Loans, net of allowance for loan losses(b)	6,210,217	5,938,039
Federal Home Loan Bank Stock	14,421	11,497
Bank Owned Life Insurance	149,319	144,503
LIABILITIES
Federal Home Loan Bank borrowings(f)	53,279	50,819
Customer repurchase agreements	159,371	176,913
Junior Subordinated Debenture Owed to Unconsolidated Subsidiary Trust	73,069	73,107
Subordinated Debt	34,659	34,635
Deposits [Member]
LIABILITIES
Time certificates of deposits(f)	6,087,206	5,763,101
Accrued Liabilities, Fair Value Disclosure	6,087,206	5,763,101
Time certificates of deposits(f)
LIABILITIES
Time certificates of deposits(f)	608,174	649,152
Accrued Liabilities, Fair Value Disclosure	605,802	647,038
Federal Home Loan Bank borrowings(f)
LIABILITIES
Federal Home Loan Bank borrowings(f)	53,279	50,819
Federal Home Loan Bank Borrowings, Fair Value Disclosure	53,227	50,898
Customer repurchase agreements and other short-term borrowings(f)
LIABILITIES
Customer repurchase agreements	159,371	176,913
Accrued Liabilities, Fair Value Disclosure	159,371	176,913
Junior subordinated debentures(g)
LIABILITIES
Junior Subordinated Debenture Owed to Unconsolidated Subsidiary Trust	73,069	73,107
Accrued Liabilities, Fair Value Disclosure	74,146	72,510
Subordinated debentures(f)
LIABILITIES
Subordinated Debt	34,659	34,635
Accrued Liabilities, Fair Value Disclosure	33,161	34,241
Significant Other Observable Inputs (Level 2) \| Deposits [Member]
LIABILITIES
Accrued Liabilities, Fair Value Disclosure	6,087,206	5,763,101
Significant Other Observable Inputs (Level 2) \| Time certificates of deposits(f)
LIABILITIES
Accrued Liabilities, Fair Value Disclosure	605,802	647,038
Significant Other Observable Inputs (Level 2) \| Federal Home Loan Bank borrowings(f)
LIABILITIES
Federal Home Loan Bank Borrowings, Fair Value Disclosure	53,227
Accrued Liabilities, Fair Value Disclosure		50,898
Significant Other Observable Inputs (Level 2) \| Junior subordinated debentures(g)
LIABILITIES
Accrued Liabilities, Fair Value Disclosure	74,146	72,510
Significant Unobservable Inputs (Level 3) \| Customer repurchase agreements and other short-term borrowings(f)
LIABILITIES
Accrued Liabilities, Fair Value Disclosure	159,371	176,913
Significant Unobservable Inputs (Level 3) \| Subordinated debentures(f)
LIABILITIES
Accrued Liabilities, Fair Value Disclosure	33,161	34,241
U.S. Treasury securities
ASSETS
Held-to-maturity Securities	1,006	1,007
Held to Maturity, Fair Value, Total	1,052	1,054
U.S. Treasury securities \| Significant Other Observable Inputs (Level 2)
ASSETS
Held to Maturity, Fair Value, Total	1,052	1,054
Agency mortgage-backed securities
ASSETS
Held-to-maturity Securities	178,358	156,088
Held to Maturity, Fair Value, Total	180,448	157,504
Agency mortgage-backed securities \| Significant Other Observable Inputs (Level 2)
ASSETS
Held to Maturity, Fair Value, Total	180,448	157,504
Agency collateralized mortgage obligations
ASSETS
Held-to-maturity Securities	288,428	297,445
Held to Maturity, Fair Value, Total	286,832	294,650
Agency collateralized mortgage obligations \| Significant Other Observable Inputs (Level 2)
ASSETS
Held to Maturity, Fair Value, Total	286,832	294,650
Single issuer trust preferred securities issued by banks
ASSETS
Held-to-maturity Securities	1,500	1,500
Held to Maturity, Fair Value, Total	1,537	1,544
Single issuer trust preferred securities issued by banks \| Significant Other Observable Inputs (Level 2)
ASSETS
Held to Maturity, Fair Value, Total	1,537	1,544
Small Business Administration Pooled Securities [Member]
ASSETS
Held-to-maturity Securities	29,100	31,036
Held to Maturity, Fair Value, Total	29,190	30,898
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	29,190	30,898
Small Business Administration Pooled Securities [Member] \| Significant Unobservable Inputs (Level 3)
ASSETS
Held to Maturity, Fair Value, Total	0	0
Loans, net of allowance for loan losses(b)
ASSETS
Loans, net of allowance for loan losses(b)	6,173,713	5,904,065
Loans Receivable, Fair Value Disclosure	6,055,275	5,784,778
Loans, net of allowance for loan losses(b) \| Significant Unobservable Inputs (Level 3)
ASSETS
Loans Receivable, Fair Value Disclosure	6,055,275	5,784,778
Investment in Federal Home Loan Bank Stock [Member]
ASSETS
Federal Home Loan Bank Stock	14,421	11,497
Investment in Federal Home Loan Bank Stock, Fair Value Disclosure	14,421	11,497
Investment in Federal Home Loan Bank Stock [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1)
ASSETS
Investment in Federal Home Loan Bank Stock, Fair Value Disclosure	0	0
Investment in Federal Home Loan Bank Stock [Member] \| Significant Other Observable Inputs (Level 2)
ASSETS
Investment in Federal Home Loan Bank Stock, Fair Value Disclosure	14,421	11,497
Investment in Federal Home Loan Bank Stock [Member] \| Significant Unobservable Inputs (Level 3)
ASSETS
Investment in Federal Home Loan Bank Stock, Fair Value Disclosure	0	0
Cash Surrender Value [Member]
ASSETS
Cash Surrender Value, Fair Value Disclosure	149,319	144,503
Bank Owned Life Insurance	149,319	144,503
Cash Surrender Value [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1)
ASSETS
Cash Surrender Value, Fair Value Disclosure	0	0
Cash Surrender Value [Member] \| Significant Other Observable Inputs (Level 2)
ASSETS
Cash Surrender Value, Fair Value Disclosure	149,319	144,503
Cash Surrender Value [Member] \| Significant Unobservable Inputs (Level 3)
ASSETS
Cash Surrender Value, Fair Value Disclosure	$ 0	$ 0

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Financial liabilities book value.

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Fair value portion of accrued expenses.

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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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The carrying amount of a life insurance policy on an officer, executive or employee for which the reporting entity (a bank) is entitled to proceeds from the policy upon death of the insured or surrender of the insurance policy.

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Fair value portion of the amount that could be realized under a life insurance contract or contracts owned by the entity, commonly known as corporate-owned life insurance (COLI) or bank-owned life insurance (BOLI).

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Fair value portion of borrowing from Federal Home Loan Bank (FHLBank).

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Federal Home Loan Bank (FHLB) stock represents an equity interest in a FHLB. It does not have a readily determinable fair value because its ownership is restricted and it lacks a market (liquidity).

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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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Fair value of investments in debt securities classified as held-to-maturity.

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Fair value portion of investments in Federal Home Loan Bank (FHLBank) stock.

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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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Including the current and noncurrent portions, carrying value as of the balance sheet date of subordinated debt (with initial maturities beyond one year or beyond the operating cycle if longer). Subordinated debt places a lender in a lien position behind debt having a higher priority of repayment in liquidation of the entity's assets.

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