Goodwill and Intangible Assets - Narrative (Details) - USD ($)	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Sep. 30, 2017
Finite-Lived Intangible Assets [Line Items]
Amortization of intangible assets	$ 0	$ 222,000	$ 0	$ 0
Mortgage Servicing Rights
Finite-Lived Intangible Assets [Line Items]
Amortization of intangible assets	22,000	109,000	73,000	105,000
Core Deposits
Finite-Lived Intangible Assets [Line Items]
Amortization of intangible assets	$ 0	$ 222,000	$ 0	$ 0