ALLOWANCES FOR CREDIT LOSS - Narrative (Details)	12 Months Ended
Dec. 31, 2021
Receivables [Abstract]
Premiums receivable write-off Policy term (in years)	1 year
Reinsurance recoverable, valuation allowance for credit losses, unobservable data, LGD, percent	100.00%

Reinsurance Recoverable, Valuation Allowance for Credit losses, Unobservable Data, Loss Given Default Assumption, Percent

No definition available.

Name:	fnhc_ReinsuranceRecoverableValuationAllowanceForCreditLossesUnobservableDataLossGivenDefaultAssumptionPercent
Namespace Prefix:	fnhc_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration