Derivative Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Derivatives not designated as hedging instruments
Mortgage Banking Derivatives Assets, Carrying Value	$ 367	$ 609
Mortgage Banking Derivatives Liabilities, Carrying Value	73	11
Mortgage Banking Derivatives, Net Carrying Value	$ 294	$ 598

Carrying values as of the balance sheet date of all assets resulting from contracts that meet the criteria of being accounted for as derivative instruments, net of the effects of master netting arrangements.

No definition available.

Name:	fdef_DerivativeAssetsCarryingValue
Namespace Prefix:	fdef_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant