Fair Value of Assets and Liabilities (Narrative) (Details) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2019 USD ($) loan	Dec. 31, 2018 USD ($) loan
Fair Value Measurements and Fair Value of Financial Instruments [Abstract]
Number of impaired loans not requiring a valuation allowance		6
Impaired Loans, Cumulative Charge-Offs \| $	$ 251	$ 428
Number of impaired loans requiring a valuation allowance	4

The number of impaired loans during the period for which a valuation allowance was not required due to the estimated realizable value of the collateral exceeding the recorded investment in the loans.

No definition available.

Name:	nwfl_NumberOfImpairedLoansNotRequiringValuationAllowance
Namespace Prefix:	nwfl_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration