Goodwill and Other Intangibles (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	May 19, 2017
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangibles	$ 3,828		$ 3,939
Goodwill	27,618		27,618
Amortization Of Other Intangible Assets	111	$ 33	33
Core Deposits [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangibles	$ 3,624		$ 3,723
Northwest Bank Branches [Member]
Finite-Lived Intangible Assets [Line Items]
Goodwill				$ 14,985
Northwest Bank Branches [Member] | Core Deposits [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangibles				$ 4,000