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Fair Value Measurements - Summary of Assets Measured at Fair Value on a Nonrecurring Basis (Detail) - Impaired Loans Asset Net - Nonrecurring basis - USD ($) $ in Thousands | Mar. 31, 2019 | Dec. 31, 2018
--- | --- | ---
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Impaired loans, net | $ 458 | $ 391
Quoted Prices in Active Markets for Identical Assets (Level 1) |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Impaired loans, net | 0 | 0
Significant Other Observable Inputs (Level 2) |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Impaired loans, net | 0 | 0
Significant Unobservable Inputs (Level 3) |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Impaired loans, net | $ 458 | $ 391

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