components of Salisbury's net deferred tax assets (Details) - SEC Schedule, 12-09, Valuation Allowance, Deferred Tax Asset [Member] - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Valuation Allowance [Line Items]
Allowance for loan losses	$ 3,355	$ 2,174
Interest on non-performing loans	214	244
Accrued deferred compensation	517	493
Post-retirement benefits	11	11
Other real estate owned write-downs		30
Restricted stock awards	196	220
Deferred loan fees, net	90	(0)
Loss on equity securities		2
Other	98	139
Gross deferred tax assets	4,481	3,313
Deferred loan costs, net		(329)
Mark-to-market purchase accounting adjustments	(8)	(44)
Goodwill and core deposit intangible asset	(590)	(570)
Accelerated depreciation	(522)	(703)
Gain on equity securities	(2)
Mortgage servicing rights	(150)	(58)
Net unrealized holding gains on available-for-sale securities	(797)	(360)
Gross deferred tax liabilities	(2,069)	(2,064)
Net deferred tax asset	$ 2,412	$ 1,249