Commitments, Guarantees and Contingent Liabilities (Details Textual) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2018	Dec. 31, 2017
Line of Credit Facility, Period	60 days or less
Commitments and Loans, Available to Sell	$ 16.8	$ 14.9

Represents commitments and loans available to sell at the reporting period.

No definition available.

Name:	fdef_CommitmentsAndLoansAvailableToSell
Namespace Prefix:	fdef_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant