Derivatives - Summary of Customer Related Interest Rate Swaps (Details) - Interest Rate Swaps - USD ($)	Sep. 30, 2018	Dec. 31, 2017
Derivative [Line Items]
Interest rate swap, Notional amount	$ 74,398,000	$ 83,726,000
Pay fixed/receive variable swaps
Derivative [Line Items]
Interest rate swap, Notional amount	37,199,000	41,863,000
Interest rate swap, Estimated fair value	492,000	55,000
Pay variable/receive fixed swaps
Derivative [Line Items]
Interest rate swap, Notional amount	37,199,000	41,863,000
Interest rate swap, Estimated fair value	$ (492,000)	$ (55,000)