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Fair Value Measurements (Details 3) - USD ($) $ in Thousands | Jun. 30, 2018 | Dec. 31, 2017
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Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Trading Securities, Equity |  | $ 20,133 | $ 0
ASSETS |  |  |
Held-to-maturity Securities |  | 538,261 | 497,688
Held to Maturity, Fair Value, Total |  | 523,288 | 494,194
Loans, net of allowance for loan losses(b) |  | 6,416,714 | 6,294,910
Federal Home Loan Bank Stock |  | 13,107 | 11,597
Bank Owned Life Insurance |  | 153,574 | 151,528
LIABILITIES |  |  |
Federal Home Loan Bank borrowings(f) |  | 50,775 | 53,264
Junior Subordinated Debenture Owed to Unconsolidated Subsidiary Trust |  | 73,077 | 73,073
Subordinated Debt |  | 34,705 | 34,682
Deposits [Member] |  |  |
LIABILITIES |  |  |
Time certificates of deposits(f) | [1] | 6,353,722 | 6,084,952
Accrued Liabilities, Fair Value Disclosure | [1] | 6,353,722 | 6,084,952
Time certificates of deposits(f) |  |  |
LIABILITIES |  |  |
Time certificates of deposits(f) | [2] | 659,768 | 644,301
Accrued Liabilities, Fair Value Disclosure | [2] | 651,660 | 639,060
Federal Home Loan Bank borrowings(f) |  |  |
LIABILITIES |  |  |
Federal Home Loan Bank borrowings(f) | [2] | 50,775 | 53,264
Federal Home Loan Bank Borrowings, Fair Value Disclosure | [2] | 49,975 | 52,111
Customer repurchase agreements and other short-term borrowings(f) |  |  |
LIABILITIES |  |  |
Customer repurchase agreements | [2] | 142,235 | 162,679
Accrued Liabilities, Fair Value Disclosure | [2] | 142,235 | 162,679
Junior subordinated debentures(g) |  |  |
LIABILITIES |  |  |
Junior Subordinated Debenture Owed to Unconsolidated Subsidiary Trust | [3] | 73,077 | 73,073
Accrued Liabilities, Fair Value Disclosure | [3] | 71,192 | 74,680
Subordinated debentures(f) |  |  |
LIABILITIES |  |  |
Subordinated Debt | [2] | 34,705 | 34,682
Accrued Liabilities, Fair Value Disclosure | [2] | 31,885 | 32,707
Significant Other Observable Inputs (Level 2) | Deposits [Member] |  |  |
LIABILITIES |  |  |
Accrued Liabilities, Fair Value Disclosure | [1] | 6,353,722 | 6,084,952
Significant Other Observable Inputs (Level 2) | Time certificates of deposits(f) |  |  |
LIABILITIES |  |  |
Accrued Liabilities, Fair Value Disclosure | [2] | 651,660 | 639,060
Significant Other Observable Inputs (Level 2) | Federal Home Loan Bank borrowings(f) |  |  |
LIABILITIES |  |  |
Federal Home Loan Bank Borrowings, Fair Value Disclosure | [2] | 49,975 |
Accrued Liabilities, Fair Value Disclosure | [2] |  | 52,111
Significant Other Observable Inputs (Level 2) | Junior subordinated debentures(g) |  |  |
LIABILITIES |  |  |
Accrued Liabilities, Fair Value Disclosure | [3] | 71,192 | 74,680
Significant Unobservable Inputs (Level 3) | Customer repurchase agreements and other short-term borrowings(f) |  |  |
LIABILITIES |  |  |
Accrued Liabilities, Fair Value Disclosure | [2] | 142,235 | 162,679
Significant Unobservable Inputs (Level 3) | Subordinated debentures(f) |  |  |
LIABILITIES |  |  |
Accrued Liabilities, Fair Value Disclosure | [2] | 31,885 | 32,707
Fair Value, Measurements, Recurring [Member] | Equity Securities [Member] |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Trading Securities, Equity |  | 20,133 |
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) | Equity Securities [Member] |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Trading Securities, Equity |  | 20,133 |
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) | Equity Securities [Member] |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Trading Securities, Equity |  | 0 |
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) | Equity Securities [Member] |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Trading Securities, Equity |  | 0 |
U.S. Treasury securities |  |  |
ASSETS |  |  |
Held-to-maturity Securities | [4] | 1,005 | 1,006
Held to Maturity, Fair Value, Total | [4] | 1,014 | 1,035
U.S. Treasury securities | Significant Other Observable Inputs (Level 2) |  |  |
ASSETS |  |  |
Held to Maturity, Fair Value, Total | [4] | 1,014 | 1,035
Agency mortgage-backed securities |  |  |
ASSETS |  |  |
Held-to-maturity Securities | [4] | 186,299 | 204,768
Held to Maturity, Fair Value, Total | [4] | 182,000 | 205,823
Agency mortgage-backed securities | Significant Other Observable Inputs (Level 2) |  |  |
ASSETS |  |  |
Held to Maturity, Fair Value, Total | [4] | 182,000 | 205,823
Agency collateralized mortgage obligations |  |  |
ASSETS |  |  |
Held-to-maturity Securities | [4] | 323,746 | 262,998
Held to Maturity, Fair Value, Total | [4] | 313,342 | 258,408
Agency collateralized mortgage obligations | Significant Other Observable Inputs (Level 2) |  |  |
ASSETS |  |  |
Held to Maturity, Fair Value, Total | [4] | 313,342 | 258,408
Single issuer trust preferred securities issued by banks |  |  |
ASSETS |  |  |
Held-to-maturity Securities | [4] | 1,500 | 1,500
Held to Maturity, Fair Value, Total | [4] | 1,523 | 1,529
Single issuer trust preferred securities issued by banks | Significant Other Observable Inputs (Level 2) |  |  |
ASSETS |  |  |
Held to Maturity, Fair Value, Total | [4] | 1,523 | 1,529
Small Business Administration Pooled Securities [Member] |  |  |
ASSETS |  |  |
Held-to-maturity Securities | [4] | 25,711 | 27,416
Held to Maturity, Fair Value, Total | [4] | 25,409 | 27,399
Small Business Administration Pooled Securities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) |  |  |
ASSETS |  |  |
Held to Maturity, Fair Value, Total | [4] | 0 | 0
Small Business Administration Pooled Securities [Member] | Significant Other Observable Inputs (Level 2) |  |  |
ASSETS |  |  |
Held to Maturity, Fair Value, Total | [4] | 25,409 | 27,399
Small Business Administration Pooled Securities [Member] | Significant Unobservable Inputs (Level 3) |  |  |
ASSETS |  |  |
Held to Maturity, Fair Value, Total | [4] | 0 | 0
Loans, net of allowance for loan losses(b) |  |  |
ASSETS |  |  |
Loans, net of allowance for loan losses(b) | [5] | 6,380,982 | 6,261,343
Loans Receivable, Fair Value Disclosure | [5] | 6,198,830 | 6,116,051
Loans, net of allowance for loan losses(b) | Significant Unobservable Inputs (Level 3) |  |  |
ASSETS |  |  |
Loans Receivable, Fair Value Disclosure | [5] | 6,198,830 | 6,116,051
Investment in Federal Home Loan Bank Stock [Member] |  |  |
ASSETS |  |  |
Federal Home Loan Bank Stock | [6] | 13,107 | 11,597
Investment in Federal Home Loan Bank Stock, Fair Value Disclosure | [6] | 13,107 | 11,597
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 | [6] | 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 | [6] | 13,107 | 11,597
Investment in Federal Home Loan Bank Stock [Member] | Significant Unobservable Inputs (Level 3) |  |  |
ASSETS |  |  |
Investment in Federal Home Loan Bank Stock, Fair Value Disclosure | [6] | 0 | 0
Cash Surrender Value [Member] |  |  |
ASSETS |  |  |
Cash Surrender Value, Fair Value Disclosure | [7] | 153,574 | 151,528
Bank Owned Life Insurance | [7] | 153,574 | 151,528
Cash Surrender Value [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) |  |  |
ASSETS |  |  |
Cash Surrender Value, Fair Value Disclosure | [7] | 0 | 0
Cash Surrender Value [Member] | Significant Other Observable Inputs (Level 2) |  |  |
ASSETS |  |  |
Cash Surrender Value, Fair Value Disclosure | [7] | 153,574 | 151,528
Cash Surrender Value [Member] | Significant Unobservable Inputs (Level 3) |  |  |
ASSETS |  |  |
Cash Surrender Value, Fair Value Disclosure | [7] | $ 0 | $ 0
[1] | Fair value of demand deposits, savings and interest checking accounts and money market deposits is the amount payable on demand at the reporting date.
[2] | Fair value was determined by discounting anticipated future cash payments using rates currently available for instruments with similar remaining maturities.
[3] | Fair value was determined based upon market prices of securities with similar terms and maturities.
[4] | The fair values presented are based on quoted market prices, where available. If quoted market prices are not available, fair values are based on quoted market prices of comparable instruments and/or discounted cash flow analysis.
[5] | In accordance with recent accounting guidance, the fair value of loans as of June 30, 2018 was measured using the exit price valuation method, determined primarily by discounting the future cash flows using the current rates at which similar loans would be made to borrowers with similar credit ratings and for the same remaining maturities or cash flows, while incorporating liquidity and credit assumptions. Previously the fair value of loans as of December 31, 2017 was estimated solely by discounting the future cash flows using the current rates at which similar loans would be made to borrowers with similar credit ratings and for the same remaining maturities or cash flows. Additionally, this amount excludes collateral dependent impaired loans, which are deemed to be marked to fair value on a nonrecurring basis.
[6] | FHLB stock has no quoted market value and is carried at cost, therefore the carrying amount approximates fair value.
[7] | Cash surrender value of life insurance is recorded at its cash surrender value (or the amount that can be realized upon surrender of the policy), therefore carrying amount approximates fair value.

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- Definition 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. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 470 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6479118&loc=d3e64650-112822 + Details
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- Definition 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. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.10) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 + Details
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- Definition 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. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=82891408&loc=d3e4428-111522 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.7) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 + Details
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