Note 9 - Acquisition - Consideration Paid (Details)	Jul. 01, 2021 USD ($) $ / shares shares
Value assigned to FDBC common share (6/30/2021 closing price) (in dollars per share) | $ / shares	$ 54.10
Landmark Bancorp Inc. [Member]
Exchange ratio	0.272
Total FDBC shares issued (in shares) | shares	647,990
Purchase price assigned to Landmark common shares exchanged for FDBC common shares	$ 35,056,259
Cash consideration (per Landmark share) (in dollars per share) | $ / shares	$ 3.26
Cash portion of purchase price	$ 7,767,586
Cash portion of purchase price (cash paid fractional shares)	5,559
Cash for outstanding Landmark stock options	69,250
Total consideration paid	$ 42,898,654
Landmark Bancorp Inc. [Member]
Landmark shares settled for stock (in shares) | shares	2,382,695