Investment Securities - Additional Information (Details)	Jun. 30, 2018 USD ($) Security	Dec. 31, 2017 USD ($) Security
Schedule of Available for Sale Securities and Held to Maturity Securities [Line Items]
Number of debt securities with unrealized losses | Security	158	118
Aggregate depreciation percentage of gross unrealized losses from amortized cost	2.58%	1.49%
Number of equity securities with unrealized losses | Security		1
Maximum
Schedule of Available for Sale Securities and Held to Maturity Securities [Line Items]
Percentage of unrealized loss on amortized cost	9.39%	10.90%
Unrealized loss of amortized cost basis | $	$ 47,000	$ 73,000
Unrealized dollar loss of amortized cost basis | $	$ 248,000	$ 185,000
Percentage of unrealized dollar loss on amortized cost	4.95%	3.71%