Quarterly Information (Unaudited) - Summary of the Company's Quarterly Financial Information (Parenthetical) (Detail) - USD ($) $ in Thousands |
1 Months Ended | 3 Months Ended | 12 Months Ended | |||
---|---|---|---|---|---|---|
Sep. 30, 2017 |
Dec. 31, 2017 |
Sep. 30, 2017 |
Mar. 31, 2017 |
Dec. 31, 2017 |
Dec. 31, 2015 |
|
Quarterly Information [Line Items] | ||||||
Tax benefit related to the exercise of stock options | $ 1,500 | |||||
Incremental hurricane allowance for credit losses | $ 3,000 | |||||
Provisional benefit to income tax expense, Tax Act | $ 3,100 | $ 3,122 | ||||
Bulk Sale of Charged Off Loans [Member] | ||||||
Quarterly Information [Line Items] | ||||||
Recovery from bulk sale of previously charged-off customer accounts in bankruptcy | $ 1,000 | $ 1,000 | $ 2,000 |