ACQUISITION - Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	12 Months Ended
	Nov. 29, 2018	Dec. 31, 2018	Dec. 31, 2017	Nov. 30, 2017
Assets of acquired bank:
Goodwill		$ 201,116	$ 201,246
Diboll State Bancshares, Inc.
Assets of acquired bank:
Cash, cash equivalents and amounts due from banks		115,598		$ 115,598
Other investments		610		610
Securities available for sale		234,447		234,447
Loans		621,318		621,318
Property and equipment		26,256		26,256
Other assets		7,052		7,052
Core deposit intangible		14,700		14,700
Trust relationship intangible		5,400		5,400
Goodwill		109,596	$ 109,726	109,726
Liabilities of acquired bank:
Deposits		(899,307)		(899,307)
Deferred tax liability, net		(7,718)		(7,802)
Other liabilities		(3,647)		(3,693)
Fair value of assets acquired net of liabilities assumed		$ 224,305		$ 224,305
Measurement Period Adjustments
Cash, cash equivalents and amounts due from banks	$ 0
Other investments	0
Securities available for sale	0
Loans	0
Property and equipment	0
Other assets	0
Core deposit intangible	0
Trust relationship intangible	0
Goodwill	(130)
Deposits	0
Deferred tax liability, net	(84)
Other liabilities	(46)
Fair value of assets acquired net of liabilities assumed	$ 0