Annual report pursuant to Section 13 and 15(d)

Borrowings - Additional Information (Detail)

v3.8.0.1
Borrowings - Additional Information (Detail) - USD ($)
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Federal Home Loan Banks [Abstract]      
Pledged loans receivable, carrying value $ 1,100,000,000    
Total borrowing capacity available from the collateral 802,900,000    
Available borrowing capacity 652,900,000    
Available for use through the Fed Discount Window 8,500,000    
Pledged loans, carrying values 9,000,000    
Borrowings 0    
Advances from the FHLB 150,000,000 $ 315,000,000  
Increase in the advances from the FHLB 165,000,000    
Interest on subordinated debentures $ 1,077,000 $ 879,000 $ 76,000
Weighted-average interest rates 0.90% 0.45% 0.20%