Quarterly report pursuant to Section 13 or 15(d)

Accumulated Other Comprehensive Income - Additional Information (Detail)

v3.19.3
Accumulated Other Comprehensive Income - Additional Information (Detail) - USD ($)
 3 Months Ended 9 Months Ended
Jan. 01, 2018
Sep. 30, 2019
Sep. 30, 2018
Sep. 30, 2019
Sep. 30, 2018
Accumulated Other Comprehensive Income [Line Items]          
Net gain (loss) on sales of securities   $ 0 $ 19,000 $ 1,295,000 $ (341,000)
Net unrealized gains (losses) recorded in comprehensive income   0 21,000 586,000 116,000
Unrealized Gains and Losses on Available for Sale Securities          
Accumulated Other Comprehensive Income [Line Items]          
Reduction of unrealized losses related to securities $ 529,000       529,000
Accumulated Other Comprehensive Income (Loss)          
Accumulated Other Comprehensive Income [Line Items]          
Adjustment to accumulated other comprehensive income related to adoption of ASU 2016-01 and 2018-02, net of tax 17,000       17,000
Tax Benefit (Expense)          
Accumulated Other Comprehensive Income [Line Items]          
Reduction in tax benefits upon adoption of ASUs $ 546,000       (546,000)
Reclassification out of Accumulated Other Comprehensive Income | Unrealized Gains and Losses on Available for Sale Securities          
Accumulated Other Comprehensive Income [Line Items]          
Net gain (loss) on sales of securities   $ 0 $ 19,000 $ 1,300,000 $ (87,000)