Loans (Composition of Total Loans Outstanding) (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 930,521		$ 934,971
Less allowance for credit losses	(6,672)	$ (6,719)	(6,675)	$ (6,188)	$ (6,145)	$ (5,843)
Net loans	923,849		928,296
Residential Mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	98,802		99,932
Less allowance for credit losses	(133)	(156)	(161)	(207)	(226)	(221)
Commercial Mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	521,060		535,735
Less allowance for credit losses	(3,579)	(3,493)	(3,647)	(3,076)	(2,987)	(2,856)
Commercial Term [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	179,294		166,335
Less allowance for credit losses	(1,144)	(1,189)	(1,062)	(889)	(904)	(845)
Commercial Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	77,060		76,302
Less allowance for credit losses	(1,032)	(1,080)	(1,032)	(1,355)	(1,219)	(1,128)
Consumer: Home Equity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	49,492		51,536
Less allowance for credit losses	(209)	(183)	(190)	(196)	(176)	(183)
Consumer: Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	4,813		5,131
Less allowance for credit losses	$ (39)	$ (43)	$ (46)	$ (49)	$ (55)	$ (63)

DNB FINANCIAL CORP /PA/ 10-Q