SEGMENT REPORTING (Operating Segments and Reconciliation of Information to Condensed Consolidated Financial Statements) (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Segment Reporting Information [Line Items]
Interest income	$ 83,858	$ 88,183
Interest expense	19,524	21,433
Provision for credit losses	24,469	(128)	$ 4,684
Noninterest income	18,168	16,969
Noninterest expense	47,746	44,192
Income before income taxes	10,287	39,655
Income tax expense	300	9,338
Net income	9,987	30,317
Assets	8,929,602	8,327,900	$ 8,629,002
Intersegment Elimination
Segment Reporting Information [Line Items]
Interest income	(4)	(3)
Interest expense	(4)	(3)
Provision for credit losses	0	0
Noninterest income	(204)	(167)
Noninterest expense	(204)	(167)
Income before income taxes	0	0
Income tax expense	0	0
Net income	0	0
Assets	(54,791)	(30,324)
Community Banking
Segment Reporting Information [Line Items]
Interest income	83,857	88,183
Interest expense	19,528	21,436
Provision for credit losses	24,469	(128)
Noninterest income	13,977	12,707
Noninterest expense	44,655	41,211
Income before income taxes	9,182	38,371
Income tax expense	1	8,993
Net income	9,181	29,378
Assets	8,917,849	8,326,141
Insurance
Segment Reporting Information [Line Items]
Interest income	3	1
Interest expense	0	0
Provision for credit losses	0	0
Noninterest income	2,129	1,904
Noninterest expense	1,464	1,420
Income before income taxes	668	485
Income tax expense	185	135
Net income	483	350
Assets	10,887	11,519
Investment Management
Segment Reporting Information [Line Items]
Interest income	2	2
Interest expense	0	0
Provision for credit losses	0	0
Noninterest income	2,266	2,525
Noninterest expense	1,831	1,728
Income before income taxes	437	799
Income tax expense	114	210
Net income	323	589
Assets	$ 55,657	$ 20,564