11) Reinsurance, Commitments and Contingencies: Other Contingencies and Commitments (Details)	Mar. 31, 2020 USD ($)
Text Block [Abstract]
Commitments to fund new residential construction loans	$ 135,902,000
Commitments to fund new residential construction loans funded	$ 94,834,000

Represents the monetary amount of Commitments to fund new residential construction loans funded, as of the indicated date.

No definition available.

Name:	snfc_CommitmentsToFundNewResidentialConstructionLoansFunded
Namespace Prefix:	snfc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant