Goodwill and Intangible Assets Mortgage Servicing Rights (Details) - USD ($)		3 Months Ended		12 Months Ended
	Sep. 08, 2016	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Amortization of Intangible Assets		$ (505,000)	$ (547,000)
Mortgage Servicing Rights [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived Intangible Assets Acquired	$ 1,069,000
Amortization of Intangible Assets		(39,000)	$ (30,000)	$ (141,000)
Finite-Lived Intangible Assets, Net		$ 805,000		$ 844,000	$ 985,000