Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies - Additional Information (Detail)

v3.10.0.1
Summary of Significant Accounting Policies - Additional Information (Detail)
$ in Thousands
 3 Months Ended 12 Months Ended
Sep. 30, 2016
USD ($)
Dec. 31, 2018
USD ($)
branch
Segment
shares
Dec. 31, 2017
USD ($)
Dec. 31, 2016
USD ($)
Jan. 01, 2019
USD ($)
Aug. 31, 2018
shares
Financing Receivable, Recorded Investment, Past Due [Line Items]            
Number of reportable segments | Segment   1        
Proceeds from redemption of FRB stock $ 14,400 $ 0 $ 0 $ 14,423    
Estimated loss emergence period   2 years 6 months 2 years 6 months 2 years 6 months    
Full Service            
Financing Receivable, Recorded Investment, Past Due [Line Items]            
Number of branches | branch   39        
Loan Production            
Financing Receivable, Recorded Investment, Past Due [Line Items]            
Number of branches | branch   9        
Equipment Financing Receivable | Minimum            
Financing Receivable, Recorded Investment, Past Due [Line Items]            
Intangible asset amortization period   1 year        
Equipment Financing Receivable | Maximum            
Financing Receivable, Recorded Investment, Past Due [Line Items]            
Intangible asset amortization period   7 years        
Stock Repurchase Program            
Financing Receivable, Recorded Investment, Past Due [Line Items]            
Number of shares authorized for repurchase (percent)           5.00%
Number of shares authorized for repurchase under program (shares) | shares           1,600,000
Shares repurchased (shares) | shares   1,600,000.0        
Shares repurchased   $ 36,100        
ASU 2016-02 | Expected            
Financing Receivable, Recorded Investment, Past Due [Line Items]            
Right-of-use asset (less than)         $ 50,000