BUSINESS COMBINATIONS, West Texas State Bank (Details) $ in Thousands		6 Months Ended		12 Months Ended
	Nov. 12, 2019 USD ($) Branch	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Business Combinations [Abstract]
Increase in goodwill		$ 1,211		$ 0
Assets Acquired and Liabilities Assumed [Abstract]
Cash paid		687	$ 0
Liabilities assumed [Abstract]
Goodwill recorded in acquisition		19,968		18,757	$ 0
West Texas State Bank [Member]
Business Combinations [Abstract]
Number of additional branches | Branch	6
Ownership interest	100.00%
Goodwill recognized expected to be deductible for income tax purposes	$ 0
Acquisition expenses				$ 955
Non-credit impaired loans fair value	196,200
Contractual balance of non-credit impaired loans	198,400
Discount on acquired loans to be recognized into interest income	2,200
Increase in goodwill		1,200
Decrease in loans		(900)
Increase in other liabilities		$ 300
Assets Acquired and Liabilities Assumed [Abstract]
Cash paid	76,100
Assets acquired [Abstract]
Cash and cash equivalents	77,903
Interest-bearing time deposits in banks	52,700
Federal funds purchased	26,468
Securities available for sale	68,398
Loans held for investment	195,228
Bank-owned life insurance	10,932
Premises and equipment, net	4,132
Accrued interest receivable	1,114
Other assets	2,648
Total assets acquired	446,202
Liabilities assumed [Abstract]
Deposits	386,176
Accrued interest payable	55
Deferred tax liability	762
Other liabilities	2,884
Total liabilities assumed	389,877
Net assets acquired	56,325
Goodwill recorded in acquisition	19,775
West Texas State Bank [Member] | Core Deposit Intangible [Member]
Assets acquired [Abstract]
Intangible assets	$ 6,679