BORROWING ARRANGEMENTS, Junior Subordinated Deferrable Interest Debentures and Trust Preferred Securities (Details) - USD ($) $ in Thousands			12 Months Ended
		Nov. 08, 2023	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2018
Detail of debentures and TPS [Abstract]
Amount of debentures			$ 46,393	$ 46,393
Subordinated Debt [Member]
Junior Subordinated Deferrable Interest Debentures and Trust Preferred Securities [Abstract]
Debt instrument, face amount			64,100	$ 64,100
Trust Preferred Securities [Member]
Junior Subordinated Deferrable Interest Debentures and Trust Preferred Securities [Abstract]
Common capital securities issued by the trusts			1,400
Detail of debentures and TPS [Abstract]
Amount of TPS			45,000
Debentures [Member]
Detail of debentures and TPS [Abstract]
Amount of debentures			$ 46,393
Debentures and Trust Preferred Securities [Member] | Maximum [Member]
Junior Subordinated Deferrable Interest Debentures and Trust Preferred Securities [Abstract]
Number of consecutive years during which interest can be deferred			5 years
Detail of debentures and TPS [Abstract]
Period after issue date when debt securities may be redeemed			5 years
SPFCT III [Member] | Trust Preferred Securities [Member]
Detail of debentures and TPS [Abstract]
Amount of TPS			$ 10,000
SPFCT III [Member] | Debentures [Member]
Detail of debentures and TPS [Abstract]
Amount of debentures			$ 10,310
SPFCT III [Member] | Debentures and Trust Preferred Securities [Member]
Junior Subordinated Deferrable Interest Debentures and Trust Preferred Securities [Abstract]
Debt instrument, maturity date	[1]		Dec. 31, 2034
Detail of debentures and TPS [Abstract]
Issue date			Dec. 31, 2004
Stated maturity date	[1]		Dec. 31, 2034
Variable Rate Basis	[2],[3]		3-mo. CME Term SOFR + 291bps; 7.54%
Term of variable rate	[2],[3]		3 months
Debt Instrument, Variable Interest Rate, Type [Extensible Enumeration]	[2],[3]		spfi:ChicagoMercantileExchangeTermSecuredOvernightFinancingRateSOFRRateMember
Basis spread on variable rate	[2],[3]		2.91%
Interest rate	[2],[3]		7.54%
SPFCT IV [Member] | Trust Preferred Securities [Member]
Detail of debentures and TPS [Abstract]
Amount of TPS			$ 20,000
SPFCT IV [Member] | Debentures [Member]
Detail of debentures and TPS [Abstract]
Amount of debentures			$ 20,619
SPFCT IV [Member] | Debentures and Trust Preferred Securities [Member]
Junior Subordinated Deferrable Interest Debentures and Trust Preferred Securities [Abstract]
Debt instrument, maturity date	[1]		Dec. 31, 2035
Detail of debentures and TPS [Abstract]
Issue date			Dec. 31, 2005
Stated maturity date	[1]		Dec. 31, 2035
Variable Rate Basis	[2],[3]		3-mo. CME Term SOFR + 165bps; 6.01%
Term of variable rate	[2],[3]		3 months
Debt Instrument, Variable Interest Rate, Type [Extensible Enumeration]	[2],[3]		spfi:ChicagoMercantileExchangeTermSecuredOvernightFinancingRateSOFRRateMember
Basis spread on variable rate	[2],[3]		1.65%
Interest rate	[2],[3]		6.01%
SPFCT V [Member] | Trust Preferred Securities [Member]
Detail of debentures and TPS [Abstract]
Amount of TPS			$ 15,000
SPFCT V [Member] | Debentures [Member]
Detail of debentures and TPS [Abstract]
Amount of debentures			$ 15,464
SPFCT V [Member] | Debentures and Trust Preferred Securities [Member]
Junior Subordinated Deferrable Interest Debentures and Trust Preferred Securities [Abstract]
Debt instrument, maturity date	[1]		Dec. 31, 2037
Detail of debentures and TPS [Abstract]
Issue date			Dec. 31, 2007
Stated maturity date	[1]		Dec. 31, 2037
Variable Rate Basis	[2],[3]		3-mo. CME Term SOFR + 176bps; 6.12%
Term of variable rate	[2],[3]		3 months
Debt Instrument, Variable Interest Rate, Type [Extensible Enumeration]	[2],[3]		spfi:ChicagoMercantileExchangeTermSecuredOvernightFinancingRateSOFRRateMember
Basis spread on variable rate	[2],[3]		1.76%
Interest rate	[2],[3]		6.12%
Subordinated Debt Securities Issued in December 2018 [Member] | Subordinated Debt [Member]
Junior Subordinated Deferrable Interest Debentures and Trust Preferred Securities [Abstract]
Debt instrument, face amount					$ 26,500
Subordinated Debt Securities Issued in December 2018 [Member] | Subordinated Debt [Member] | Debt Securities One [Member]
Junior Subordinated Deferrable Interest Debentures and Trust Preferred Securities [Abstract]
Debt instrument, maturity date		Dec. 15, 2023	Dec. 31, 2028
Debt instrument, face amount		$ 12,400			$ 12,400
Detail of debentures and TPS [Abstract]
Stated maturity date		Dec. 15, 2023	Dec. 31, 2028

[1] May be redeemed five years from the issue date, the Company has no current plans to redeem;

[2] Interest payable quarterly with principal due at maturity;

[3] Rate as of last reset date.