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Fair Value Measurements - Fair Value Inputs, Quantitative Information (Details) - USD ($) | 3 Months Ended |
--- | --- | ---
Mar. 31, 2018 | Mar. 31, 2017 | Dec. 31, 2017
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |  |
Write downs on OREO properties | $ 0 | $ 0 |
Impaired Loans | Minimum | Market Approach Valuation Technique |  |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |  |
Discount rate of long-lived assets to be disposed of by sale | 0.00% |  |
Impaired Loans | Maximum | Market Approach Valuation Technique |  |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |  |
Discount rate of long-lived assets to be disposed of by sale | 78.10% |  |
Impaired Loans | Weighted Average | Market Approach Valuation Technique |  |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |  |
Discount rate of long-lived assets to be disposed of by sale | 26.10% |  |
Other Real Estate Owned | Minimum | Market Approach Valuation Technique |  |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |  |
Discount rate of long-lived assets to be disposed of by sale | 8.00% |  |
Other Real Estate Owned | Maximum | Market Approach Valuation Technique |  |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |  |
Discount rate of long-lived assets to be disposed of by sale | 96.20% |  |
Other Real Estate Owned | Weighted Average | Market Approach Valuation Technique |  |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |  |
Discount rate of long-lived assets to be disposed of by sale | 11.60% |  |
Asses to be Disposed of by Sale | Minimum | Market Approach Valuation Technique |  |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |  |
Discount rate of long-lived assets to be disposed of by sale | 0.00% |  |
Asses to be Disposed of by Sale | Maximum | Market Approach Valuation Technique |  |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |  |
Discount rate of long-lived assets to be disposed of by sale | 0.00% |  |
Asses to be Disposed of by Sale | Weighted Average | Market Approach Valuation Technique |  |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |  |
Discount rate of long-lived assets to be disposed of by sale | 0.00% |  |
Carrying Amount |  |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |  |
Net loans held for investment | $ 7,614,500,000 |  | $ 7,542,200,000
Change During Period | Fair Value Measured on a Non-recurring Basis |  |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |  |
Fair Value of long-lived assets to be disposed of by sale |  |  | 0
Estimated Fair Value |  |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |  |
Net loans held for investment | 7,388,200,000 |  | 7,298,800,000
Estimated Fair Value | Fair Value Measured on a Non-recurring Basis |  |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |  |
Impaired loans | 36,000,000 |  | 32,600,000
Other real estate owned | 1,300,000 |  | 1,300,000
Fair Value of long-lived assets to be disposed of by sale | 800,000 |  | 800,000
Significant Unobservable Inputs (Level 3) | Fair Value Measured on a Non-recurring Basis |  |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |  |
Impaired loans |  |  | 32,600,000
Other real estate owned | 1,300,000 |  | 1,300,000
Fair Value of long-lived assets to be disposed of by sale | 800,000 |  | 800,000
Significant Unobservable Inputs (Level 3) | Carrying Amount | Fair Value Measured on a Non-recurring Basis |  |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |  |
Impaired loans | 57,700,000 |  | 54,800,000
Fair Value of long-lived assets to be disposed of by sale |  |  | 800,000
Significant Unobservable Inputs (Level 3) | Estimated Fair Value |  |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |  |
Net loans held for investment |  |  | 32,600,000
Impaired loans | 36,000,000 |  |
Significant Unobservable Inputs (Level 3) | Estimated Fair Value | Fair Value Measured on a Non-recurring Basis |  |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |  |
Impaired loans | $ 36,000,000 |  | $ 32,600,000

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