BUSINESS COMBINATIONS - Schedule of Recognized Identified Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands				9 Months Ended
	Feb. 21, 2020	Nov. 01, 2019	Mar. 01, 2019	Sep. 30, 2020	Sep. 30, 2019	Jun. 30, 2020
Purchase price:
Cash paid				$ 10,761	$ 0
Fair value of liabilities acquired:
Goodwill						$ 28,100
Mainland
Purchase price:
Stock issued			$ 18,637
Fair value of assets acquired:
Cash and cash equivalents			38,365
Loans			81,336
Other real estate owned			1,507
Bank premises and equipment			2,550
Core deposit intangible asset			2,439
Other assets			1,414
Total assets acquired			127,611
Fair value of liabilities acquired:
Deposits			107,646
Repurchase agreements			4,684
Other liabilities			1,883
Total liabilities assumed			114,213
Fair value of net assets acquired			13,398
Goodwill			$ 5,239
Bank of York
Purchase price:
Cash paid		$ 15,000
Fair value of assets acquired:
Cash and cash equivalents		50,776
Investments		451
Loans		46,086
Bank premises and equipment		917
Core deposit intangible asset		931
Bank owned life insurance		2,429
Other assets		344
Total assets acquired		101,934
Fair value of liabilities acquired:
Deposits		85,004
Repurchase agreements		5,641
Other liabilities		1,306
Total liabilities assumed		91,951
Fair value of net assets acquired		9,983
Goodwill		$ 5,017
Plains Capital Bank
Purchase price:
Cash paid	$ 11,114
Fair value of assets acquired:
Cash and cash equivalents	353
Loans	45,287
Bank premises and equipment	2,770
Core deposit intangible asset	170
Other assets	127
Total assets acquired	48,707
Fair value of liabilities acquired:
Deposits	36,973
Other liabilities	1,084
Total liabilities assumed	38,057
Fair value of net assets acquired	10,650
Goodwill	$ 464