SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) $ / shares in Units, $ in Thousands		3 Months Ended	9 Months Ended
	Mar. 11, 2019 $ / shares shares	Sep. 30, 2020 USD ($) $ / shares shares	Sep. 30, 2020 USD ($) $ / shares shares	Dec. 31, 2019 $ / shares shares	Mar. 10, 2019 shares
Change in Capital Structure [Abstract]
Number of shares of common stock authorized (in shares) | shares	30,000,000	30,000,000	30,000,000	30,000,000	1,000,000
Common stock, par value (in dollars per share) | $ / shares	$ 1.00	$ 1.00	$ 1.00	$ 1.00
Stock split ratio	29
Loans [Abstract]
Number of days principal or interest payments are past due for loans to be placed on nonaccrual status			90 days
Minimum [Member]
Allowance for Loan Losses [Abstract]
Threshold balance of loan to be specifically reviewed for impairment			$ 250
City Bank [Member] | Bank Subsidiary [Member]
Subsidiaries Information [Abstract]
Wholly Owned, Consolidated Subsidiaries			City Bank
Windmark Insurance Agency, Inc. ("Windmark") [Member] | Non-bank Subsidiary [Member]
Subsidiaries Information [Abstract]
Wholly Owned, Consolidated Subsidiaries			Windmark Insurance Agency, Inc. ("Windmark")
Ruidoso Retail, Inc. [Member] | Non-bank Subsidiary [Member]
Subsidiaries Information [Abstract]
Wholly Owned, Consolidated Subsidiaries			Ruidoso Retail, Inc.
CB Provence, LLC [Member] | Non-bank Subsidiary [Member]
Subsidiaries Information [Abstract]
Wholly Owned, Consolidated Subsidiaries			CB Provence, LLC
CBT Brushy Creek, LLC [Member] | Non-bank Subsidiary [Member]
Subsidiaries Information [Abstract]
Wholly Owned, Consolidated Subsidiaries			CBT Brushy Creek, LLC
CBT Properties, LLC [Member] | Non-bank Subsidiary [Member]
Subsidiaries Information [Abstract]
Wholly Owned, Consolidated Subsidiaries			CBT Properties, LLC
South Plains Financial Capital Trusts (SPFCT) III-V [Member] | Non-bank Subsidiary [Member]
Subsidiaries Information [Abstract]
Wholly Owned, Equity Method Subsidiaries			South Plains Financial Capital Trusts (SPFCT) III-V
Substandard or Worse [Member] | Minimum [Member]
Allowance for Loan Losses [Abstract]
Threshold balance of loan to be specifically reviewed for impairment		$ 250
Customer Relationships [Member]
Goodwill and Other Intangible Assets [Abstract]
Estimated useful lives			5 years
Employment Agreements [Member]
Goodwill and Other Intangible Assets [Abstract]
Estimated useful lives			5 years
Core Deposits Intangible [Member] | Maximum [Member]
Goodwill and Other Intangible Assets [Abstract]
Estimated useful lives			10 years