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Fair Value Measurements and Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Sep. 30, 2016 | Sep. 30, 2016 | Sep. 30, 2015 | Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |
Fair Value, Assets, Level 1 to Level 2 Transfers, Amount | $ 0 | $ 0 |  |
Fair Value, Assets, Level 2 to Level 1 Transfers, Amount | 0 | 0 |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3 |  | 0 |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3 |  | 0 |  |
Securities Available for Sale [Abstract] |  |  |  |
Total Securities Available for Sale | 1,288,899 | 1,288,899 |  | $ 1,174,544
Trading Securities | 8,852 | $ 8,852 |  | 8,377
Liabilities [Abstract] |  |  |  |
Decrease in goodwill | (1,200) |  |  |
Minimum [Member] |  |  |  |
Liabilities [Abstract] |  |  |  |
Liquidation expense ratio on impaired collateral |  | 10.00% |  |
Maximum [Member] |  |  |  |
Liabilities [Abstract] |  |  |  |
Liquidation expense ratio on impaired collateral |  |  | 35.00% |
Federal Agency [Member] |  |  |  |
Securities Available for Sale [Abstract] |  |  |  |
Total Securities Available for Sale | 256,093 | $ 256,093 |  | 311,272
State & Municipal [Member] |  |  |  |
Securities Available for Sale [Abstract] |  |  |  |
Total Securities Available for Sale | 38,654 | 38,654 |  | 31,637
Other Securities [Member] |  |  |  |
Securities Available for Sale [Abstract] |  |  |  |
Total Securities Available for Sale | 20,318 | 20,318 |  | 16,768
Recurring Basis [Member] |  |  |  |
Securities Available for Sale [Abstract] |  |  |  |
Total Securities Available for Sale | 1,288,899 | 1,288,899 |  | 1,174,544
Trading Securities | 8,852 | 8,852 |  | 8,377
Interest Rate Swaps | 18,977 | 18,977 |  | 6,224
Total | 1,316,728 | 1,316,728 |  | 1,189,145
Liabilities [Abstract] |  |  |  |
Interest Rate Swaps | 18,258 | 18,258 |  | 6,224
Total | 18,258 | 18,258 |  | 6,224
Recurring Basis [Member] | Quoted Prices in Active Market for Identical Assets (Level I) [Member] |  |  |  |
Securities Available for Sale [Abstract] |  |  |  |
Total Securities Available for Sale | 10,964 | 10,964 |  | 7,526
Trading Securities | 8,852 | 8,852 |  | 8,377
Interest Rate Swaps | 0 | 0 |  | 0
Total | 19,816 | 19,816 |  | 15,903
Liabilities [Abstract] |  |  |  |
Interest Rate Swaps | 0 | 0 |  | 0
Total | 0 | 0 |  | 0
Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |  |
Securities Available for Sale [Abstract] |  |  |  |
Total Securities Available for Sale | 1,277,935 | 1,277,935 |  | 1,167,018
Trading Securities | 0 | 0 |  | 0
Interest Rate Swaps | 18,977 | 18,977 |  | 6,224
Total | 1,296,912 | 1,296,912 |  | 1,173,242
Liabilities [Abstract] |  |  |  |
Interest Rate Swaps | 18,258 | 18,258 |  | 6,224
Total | 18,258 | 18,258 |  | 6,224
Recurring Basis [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |  |
Securities Available for Sale [Abstract] |  |  |  |
Total Securities Available for Sale | 0 | 0 |  | 0
Trading Securities | 0 | 0 |  | 0
Interest Rate Swaps | 0 | 0 |  | 0
Total | 0 | 0 |  | 0
Liabilities [Abstract] |  |  |  |
Interest Rate Swaps | 0 | 0 |  | 0
Total | 0 | 0 |  | 0
Recurring Basis [Member] | Federal Agency [Member] |  |  |  |
Securities Available for Sale [Abstract] |  |  |  |
Total Securities Available for Sale | 256,093 | 256,093 |  | 311,272
Recurring Basis [Member] | Federal Agency [Member] | Quoted Prices in Active Market for Identical Assets (Level I) [Member] |  |  |  |
Securities Available for Sale [Abstract] |  |  |  |
Total Securities Available for Sale | 0 | 0 |  | 0
Recurring Basis [Member] | Federal Agency [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |  |
Securities Available for Sale [Abstract] |  |  |  |
Total Securities Available for Sale | 256,093 | 256,093 |  | 311,272
Recurring Basis [Member] | Federal Agency [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |  |
Securities Available for Sale [Abstract] |  |  |  |
Total Securities Available for Sale | 0 | 0 |  | 0
Recurring Basis [Member] | State & Municipal [Member] |  |  |  |
Securities Available for Sale [Abstract] |  |  |  |
Total Securities Available for Sale | 38,654 | 38,654 |  | 31,637
Recurring Basis [Member] | State & Municipal [Member] | Quoted Prices in Active Market for Identical Assets (Level I) [Member] |  |  |  |
Securities Available for Sale [Abstract] |  |  |  |
Total Securities Available for Sale | 0 | 0 |  | 0
Recurring Basis [Member] | State & Municipal [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |  |
Securities Available for Sale [Abstract] |  |  |  |
Total Securities Available for Sale | 38,654 | 38,654 |  | 31,637
Recurring Basis [Member] | State & Municipal [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |  |
Securities Available for Sale [Abstract] |  |  |  |
Total Securities Available for Sale | 0 | 0 |  | 0
Recurring Basis [Member] | Mortgage-Backed [Member] |  |  |  |
Securities Available for Sale [Abstract] |  |  |  |
Total Securities Available for Sale | 372,364 | 372,364 |  | 409,896
Recurring Basis [Member] | Mortgage-Backed [Member] | Quoted Prices in Active Market for Identical Assets (Level I) [Member] |  |  |  |
Securities Available for Sale [Abstract] |  |  |  |
Total Securities Available for Sale | 0 | 0 |  | 0
Recurring Basis [Member] | Mortgage-Backed [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |  |
Securities Available for Sale [Abstract] |  |  |  |
Total Securities Available for Sale | 372,364 | 372,364 |  | 409,896
Recurring Basis [Member] | Mortgage-Backed [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |  |
Securities Available for Sale [Abstract] |  |  |  |
Total Securities Available for Sale | 0 | 0 |  | 0
Recurring Basis [Member] | Collateralized Mortgage Obligations [Member] |  |  |  |
Securities Available for Sale [Abstract] |  |  |  |
Total Securities Available for Sale | 601,470 | 601,470 |  | 404,971
Recurring Basis [Member] | Collateralized Mortgage Obligations [Member] | Quoted Prices in Active Market for Identical Assets (Level I) [Member] |  |  |  |
Securities Available for Sale [Abstract] |  |  |  |
Total Securities Available for Sale | 0 | 0 |  | 0
Recurring Basis [Member] | Collateralized Mortgage Obligations [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |  |
Securities Available for Sale [Abstract] |  |  |  |
Total Securities Available for Sale | 601,470 | 601,470 |  | 404,971
Recurring Basis [Member] | Collateralized Mortgage Obligations [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |  |
Securities Available for Sale [Abstract] |  |  |  |
Total Securities Available for Sale | 0 | 0 |  | 0
Recurring Basis [Member] | Other Securities [Member] |  |  |  |
Securities Available for Sale [Abstract] |  |  |  |
Total Securities Available for Sale | 20,318 | 20,318 |  | 16,768
Recurring Basis [Member] | Other Securities [Member] | Quoted Prices in Active Market for Identical Assets (Level I) [Member] |  |  |  |
Securities Available for Sale [Abstract] |  |  |  |
Total Securities Available for Sale | 10,964 | 10,964 |  | 7,526
Recurring Basis [Member] | Other Securities [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |  |
Securities Available for Sale [Abstract] |  |  |  |
Total Securities Available for Sale | 9,354 | 9,354 |  | 9,242
Recurring Basis [Member] | Other Securities [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |  |
Securities Available for Sale [Abstract] |  |  |  |
Total Securities Available for Sale | 0 | 0 |  | $ 0
Nonrecurring Basis [Member] |  |  |  |
Liabilities [Abstract] |  |  |  |
Collateral dependent impaired financing receivable with specific reserves | 9,900 | 9,900 | $ 9,900 |
Allowance for loan and lease losses collateral dependent impaired loans with specific reserves | $ 3,200 | $ 3,200 | $ 3,400 |

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