LOANS, Activity in Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
LOANS [Abstract]
Percentage of allowance for loan losses to loans held for investment	2.01%		2.05%
Allowance for Loan Losses [Roll Forward]
Beginning Balance	$ 45,553	$ 24,197
Provision for loan losses	89	6,234
Charge-offs	(841)	(1,670)
Recoveries	218	313
Ending Balance	45,019	29,074
Commercial Real Estate [Member]
Allowance for Loan Losses [Roll Forward]
Beginning Balance	18,962	5,049
Provision for loan losses	58	2,035
Charge-offs	0	0
Recoveries	0	108
Ending Balance	19,020	7,192
Commercial [Member] \| Specialized [Member]
Allowance for Loan Losses [Roll Forward]
Beginning Balance	5,760	2,287
Provision for loan losses	(378)	2,218
Charge-offs	0	(14)
Recoveries	76	64
Ending Balance	5,458	4,555
Commercial [Member] \| General [Member]
Allowance for Loan Losses [Roll Forward]
Beginning Balance	9,227	9,609
Provision for loan losses	52	(798)
Charge-offs	(344)	(848)
Recoveries	44	17
Ending Balance	8,979	7,980
Consumer [Member] \| 1-4 Family Residential [Member]
Allowance for Loan Losses [Roll Forward]
Beginning Balance	4,646	2,093
Provision for loan losses	295	651
Charge-offs	(52)	0
Recoveries	1	0
Ending Balance	4,890	2,744
Consumer [Member] \| Auto Loans [Member]
Allowance for Loan Losses [Roll Forward]
Beginning Balance	4,226	3,385
Provision for loan losses	(180)	1,316
Charge-offs	(188)	(441)
Recoveries	33	52
Ending Balance	3,891	4,312
Consumer [Member] \| Other Consumer [Member]
Allowance for Loan Losses [Roll Forward]
Beginning Balance	1,671	1,341
Provision for loan losses	4	593
Charge-offs	(257)	(367)
Recoveries	62	72
Ending Balance	1,480	1,639
Construction [Member]
Allowance for Loan Losses [Roll Forward]
Beginning Balance	1,061	433
Provision for loan losses	238	219
Charge-offs	0	0
Recoveries	2	0
Ending Balance	$ 1,301	$ 652

This element represents percentage of allowance for loan losses to loans held for investment.

No definition available.

Name:	spfi_PercentageOfAllowanceForLoanLossesToLoansHeldForInvestment
Namespace Prefix:	spfi_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of recovery of loans and lease receivables which had previously been fully or partially written-off as bad debts.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of loans and leases that have been written off from both loan receivables and allowance reserve for credit loss.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953423-111524

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-URI http://asc.fasb.org/extlink&oid=27010918&loc=d3e74567-122707

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

Amount of expense related to estimated loss from loan and lease transactions.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
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-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Balance Type:	debit
Period Type:	duration

- References

No definition available.

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