FHLB Advances and Other Borrowings (Tables)	12 Months Ended
Dec. 31, 2021
FHLB Advances and Other Borrowings [Abstract]
Schedule Of Maturity And Weighted-Average Interest Rate Of Secured Borrowings	As of December 31, 2021(dollars in thousands)Amount Rate 2022$ 766 3.25%2023 26 4.25 2024 2,700 4.13 2025 - - 2026 - - 2027 and thereafter 6,952 2.43 Total$ 10,444 2.69%

Schedule Of Secured Borrowings, Maturities And Weighted-Average Interest Rates [Table Text Block]

No definition available.

Name:	fdbc_ScheduleOfSecuredBorrowingsMaturitiesAndWeightedAverageInterestRatesTableTextBlock
Namespace Prefix:	fdbc_
Data Type:	dtr-types:textBlockItemType
Balance Type:	na
Period Type:	duration