Securities - Debt Securities, Additional Information (Details)	Jun. 30, 2018 security
Debt Securities, Available-for-sale [Line Items]
Number of securities in unrealized loss position	120
Securities in unrealized loss positions greater than or equal to one year	53
U.S. agency collateralized mortgage obligations: residential
Debt Securities, Available-for-sale [Line Items]
Number of securities in unrealized loss position	24
State and political subdivisions
Debt Securities, Available-for-sale [Line Items]
Number of securities in unrealized loss position	9
U.S. government sponsored entities and agencies
Debt Securities, Available-for-sale [Line Items]
Number of securities in unrealized loss position	8
U.S. agency mortgage-backed securities: residential
Debt Securities, Available-for-sale [Line Items]
Number of securities in unrealized loss position	6
U.S. Treasury and federal agency
Debt Securities, Available-for-sale [Line Items]
Number of securities in unrealized loss position	5
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Number of securities in unrealized loss position	1