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INCOME TAXES - Reconciliation of Effective Income Tax Rate to Statutory Federal Rate (Detail) | 12 Months Ended
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Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Income Tax Disclosure [Abstract] |  |  |  |
Statutory federal tax rate | 21.00% | 34.00% | 34.00% | 35.00%
Increase (decrease) resulting from: |  |  |  |
Tax exempt interest income | (7.70%) | (13.00%) | (16.00%) |
Earnings from life insurance | (1.70%) | (2.40%) | (4.70%) |
Disallowed interest expense | 0.80% | 1.00% | 1.00% |
Low-income housing credits and related expense | (2.50%) | (4.60%) | (7.20%) |
Merger related | 0.60% | 0.00% | 0.00% |
Expense due to enactment of federal tax reform legislation | 0.00% | 21.20% | 0.00% |
Regulatory settlement | 0.00% | 0.00% | 4.30% |
Change in statutory federal tax rate | 0.00% | 0.00% | 2.30% |
Other | 0.90% | (1.30%) | 2.30% |
Effective income tax rate | 11.40% | 34.90% | 16.00% |

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