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Commitments and Contingencies (Details) $ in Millions | Apr. 08, 2019 | Mar. 31, 2019 USD ($) | Dec. 31, 2018 USD ($) | Aug. 16, 2018
--- | --- | --- | --- | ---
Loss Contingencies [Line Items] |  |  |  |
Notional amount of terminated commitment |  | $ 539.6 | $ 467.9 |
Mortgage Loans Held for Sale |  |  |  |
Loss Contingencies [Line Items] |  |  |  |
Mortgage loans with recourse provision in effect |  | $ 1.5 |  |
Inland Northwest Bank |  |  |  |
Loss Contingencies [Line Items] |  |  |  |
Number of banking offices acquired |  |  |  | 20
Subsequent Event | Idaho Independent Bank [Member] |  |  |  |
Loss Contingencies [Line Items] |  |  |  |
Number of banking offices acquired | 11 |  |  |
Subsequent Event | Community 1st Bank [Member] |  |  |  |
Loss Contingencies [Line Items] |  |  |  |
Number of banking offices acquired | 3 |  |  |
Construction Contracts |  |  |  |
Loss Contingencies [Line Items] |  |  |  |
Unrecorded Unconditional Purchase Obligation |  |  | $ 1.5 |

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