PARENT COMPANY ONLY CONDENSED FINANCIAL INFORMATION, Condensed Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
ASSETS [Abstract]
Cash and cash equivalents	$ 158,099	$ 245,989
Other assets	30,374	26,191
Total assets	3,237,167	2,712,745
LIABILITIES AND STOCKHOLDERS' EQUITY [Abstract]
Accrued expenses and other liabilities	29,098	29,416
ESOP-owned shares		58,195
Stockholders' equity	306,182	154,580	$ 158,206
Total liabilities and stockholders' equity	3,237,167	2,712,745
South Plains Financial, Inc. [Member]
ASSETS [Abstract]
Cash and cash equivalents	4,181	22,627
Other assets	3,906	2,304
Total assets	380,430	294,011
LIABILITIES AND STOCKHOLDERS' EQUITY [Abstract]
Debt	72,865	80,395
Accrued expenses and other liabilities	1,383	841
ESOP-owned shares	0	58,195
Stockholders' equity	306,182	154,580
Total liabilities and stockholders' equity	380,430	294,011
South Plains Financial, Inc. [Member] | Bank Subsidiary [Member]
ASSETS [Abstract]
Investment in subsidiary	372,292	269,022
South Plains Financial, Inc. [Member] | Other Subsidiary [Member]
ASSETS [Abstract]
Investment in subsidiary	$ 51	$ 58