Quarterly report pursuant to Section 13 or 15(d)

Investment Securities - Additional Information (Details)

v3.8.0.1
Investment Securities - Additional Information (Details)
3 Months Ended
Mar. 31, 2018
USD ($)
Security
Mar. 31, 2017
Security
Dec. 31, 2017
USD ($)
Investments Debt And Equity Securities [Abstract]      
Available for sale securities pledged | $ $ 0   $ 0
Debt Securities, Available-for-sale, Restriction Type [Extensible List] us-gaap:CollateralPledgedMember   us-gaap:CollateralPledgedMember
Available for sale, securities in unrealized loss positions, number of positions 50    
Available for sale, securities in unrealized loss positions, number of positions, less than 12 months 44    
Available for sale securities, gross realized gain (loss), excluding other than temporary impairments | $ $ 0    
Number of securities sold 0 0