10) Reinsurance, Commitments and Contingencies: Mortgage Loan Loss Settlements (Details) - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Text Block [Abstract]
Amounts accrued for loan losses	$ 20,584,000	$ 4,046,000

Represents the monetary amount of Amounts accrued for loan losses, as of the indicated date.

No definition available.

Name:	snfc_AmountsAccruedForLoanLosses
Namespace Prefix:	snfc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant