Quarterly report pursuant to Section 13 or 15(d)

Securities - Additional Information (Detail)

v3.19.1
Securities - Additional Information (Detail) - USD ($)
3 Months Ended 12 Months Ended
Jan. 01, 2018
Mar. 31, 2019
Mar. 31, 2018
Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]        
Impairment charges on securities in continuous unrealized loss position for 12 months or longer   $ 0   $ 0
Net gain (loss) in earnings resulting from sale of securities   725,000 $ (428,000)  
Net unrealized gains (losses) recorded in comprehensive income   (206,000)    
Reduction in securities available for sale   (621,470,000)   (574,908,000)
Reduction to retained earnings   (104,771,000)   (97,539,000)
Increase in net deferred tax asset   25,600,000   27,400,000
Gross realized losses included in earnings     $ 957,000  
Available for sale securities pledged as collateral   $ 30,000,000   $ 29,900,000
ASU 2016-01        
Debt Securities, Available-for-sale [Line Items]        
Net unrealized gains (losses) recorded in comprehensive income $ (529,000)      
Reduction in securities available for sale 529,000      
Reduction to retained earnings 382,000      
Increase in net deferred tax asset $ 147,000