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Organization and Basis of Presentation - Transition to an Independent Public Company (Details) - shares |  | 12 Months Ended | 29 Months Ended
--- | --- | --- | ---
Feb. 01, 2019 | Dec. 31, 2018 | Dec. 31, 2018
BNP Paribas (BNPP) |  |  |
Reorganization Transactions |  |  |
Number of shares sold |  |  | 109,830,000
BNP Paribas (BNPP) | First Hawaiian, Inc. (FHI) |  |  |
Reorganization Transactions |  |  |
Number of shares sold | 24,859,750 |  |
Outstanding common stock owned (as a percent) | 0.00% |  |
BancWest Corporation (BWC) |  |  |
Reorganization Transactions |  |  |
Number of shares repurchased |  | 4,769,870 |

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