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Recent Developments Including Mergers and Acquisitions - Additional Information (Detail) $ in Thousands | Dec. 14, 2018 USD ($) ParkingSpaces | Aug. 31, 2018 USD ($) ft² Floor | Jan. 11, 2018 USD ($) Community Location | Mar. 31, 2019 USD ($) | Dec. 31, 2018 USD ($)
--- | --- | --- | --- | --- | ---
Business Combination Separately Recognized Transactions [Line Items] |  |  |  |  |
Goodwill |  |  |  | $ 79,749 | $ 79,749
Number of additional banking communities | Community |  |  | 5 |  |
First Bank & Trust Company [Member] |  |  |  |  |
Business Combination Separately Recognized Transactions [Line Items] |  |  |  |  |
Date of acquisition |  |  | Jan. 11, 2018 |  |
Total assets acquired |  |  | $ 290,000 |  |
Loans |  |  | 247,000 |  |
Deposits |  |  | 251,000 |  |
Intangibles assets, net |  |  | 6,300 |  |
Goodwill |  |  | $ 19,100 |  |
First Bank of Chandler [Member] |  |  |  |  |
Business Combination Separately Recognized Transactions [Line Items] |  |  |  |  |
Date of acquisition |  |  | Jan. 11, 2018 |  |
Total assets acquired |  |  | $ 88,000 |  |
Loans |  |  | 66,000 |  |
Deposits |  |  | 79,000 |  |
Intangibles assets, net |  |  | 2,200 |  |
Goodwill |  |  | $ 6,600 |  |
Number of locations acquired | Location |  |  | 2 |  |
BFTower LLC [Member] | Cotter Ranch Tower [Member] |  |  |  |  |
Business Combination Separately Recognized Transactions [Line Items] |  |  |  |  |
Contract price |  | $ 21,000 |  |  |
Number of square feet | ft² |  | 507,000 |  |  |
Number of floors | Floor |  | 36 |  |  |
Date of acquisition |  | Aug. 31, 2018 |  |  |
Percentage of property leased |  | 55.00% |  |  |
Percentage of occupancy |  | 35.00% |  |  |
Percentage of occupancy including leased space |  | 90.00% |  |  |
Renovations completion year |  | 2020 |  |  |
Renovations cost |  | $ 70,000 |  |  |
BFTower LLC [Member] | Cotter Ranch Tower [Member] | SFPG, LLC [Member] |  |  |  |  |
Business Combination Separately Recognized Transactions [Line Items] |  |  |  |  |
Ownership interest acquired | 42.60% |  |  |  |
Space of parking garage | ParkingSpaces | 1,568 |  |  |  |
Payment to acquire ownership interest | $ 9,800 |  |  |  |

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