Derivatives - Narrative (Details)	3 Months Ended
	Mar. 31, 2018 USD ($) derivative_swap	Sep. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2017 USD ($)
Derivatives, Fair Value [Line Items]
Collateral requirement threshold	$ 250,000
Collateral posted	300,000			$ 300,000
Derivative notional amount	$ 12,000,000			12,500,000
Number of derivatives | derivative_swap	2
Derivative fee income	$ 0		$ 16,000
Residential Mortgage Holding Company
Derivatives, Fair Value [Line Items]
Commitments to originate mortgage loans held for sale	64,800,000			$ 43,600,000
Variable to Fixed
Derivatives, Fair Value [Line Items]
Derivative notional amount	$ 6,000,000
Number of derivatives | derivative_swap	1
Fixed to Variable
Derivatives, Fair Value [Line Items]
Derivative notional amount	$ 6,000,000
Number of derivatives | derivative_swap	1
Subordinated Debt
Derivatives, Fair Value [Line Items]
Junior subordinated debenture		$ 10,000,000.0
Junior subordinated debenture, effective interest rate		3.72%
Debt instrument, interest rate during period	3.49%
Subordinated Debt | LIBOR
Derivatives, Fair Value [Line Items]
Debt instrument, basis spread on variable rate		1.37%
Designated as Hedging Instrument | Interest rate swaps
Derivatives, Fair Value [Line Items]
Cash pledged to collateralize fair value exposure on interest rate swap	$ 400,000
Unrealized gain on interest rate swap	$ 651,000