SEGMENT REPORTING (Operating Segments and Reconciliation of Information to Condensed Consolidated Financial Statements) (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Segment Reporting Information [Line Items]
Interest income	$ 48,576	$ 41,803	$ 94,534	$ 83,456
Interest expense	6,250	5,071	11,955	10,602
Provision (credit)	1,322	2,957	1,516	4,193	$ 5,546
Non-interest income	13,571	12,751	26,203	26,114
Non-interest Expense	32,868	30,871	62,849	63,188
Income before income taxes	21,707	15,655	44,417	31,587
Income tax expense	6,966	5,008	14,564	10,127
Net income	14,741	10,647	29,853	21,460
Assets	5,270,521	4,739,449	5,270,521	4,739,449	$ 5,091,383
Intersegment Elimination
Segment Reporting Information [Line Items]
Interest income	(2)	(2)	(4)	(4)
Interest expense	(2)	(2)	(4)	(4)
Provision (credit)	0	0	0	0
Non-interest income	(210)	(178)	(419)	(356)
Non-interest Expense	(210)	(178)	(419)	(356)
Income before income taxes	0	0	0	0
Income tax expense	0	0	0	0
Net income	0	0	0	0
Assets	(25,024)	(20,274)	(25,024)	(20,274)
Community Banking
Segment Reporting Information [Line Items]
Interest income	48,576	41,804	94,533	83,457
Interest expense	6,252	5,073	11,959	10,606
Provision (credit)	1,322	2,957	1,516	4,193
Non-interest income	10,544	10,136	19,630	20,355
Non-interest Expense	30,602	28,999	58,401	59,379
Income before income taxes	20,944	14,911	42,287	29,634
Income tax expense	6,669	4,718	13,729	9,362
Net income	14,275	10,193	28,558	20,272
Assets	5,273,823	4,742,368	5,273,823	4,742,368
Insurance
Segment Reporting Information [Line Items]
Interest income	0	0	1	1
Interest expense	0	0	0	0
Provision (credit)	0	0	0	0
Non-interest income	1,223	950	2,975	2,403
Non-interest Expense	1,324	1,030	2,679	2,201
Income before income taxes	(101)	(80)	297	203
Income tax expense	(40)	(31)	121	83
Net income	(61)	(49)	176	120
Assets	8,046	5,754	8,046	5,754
Investment Management
Segment Reporting Information [Line Items]
Interest income	2	1	4	2
Interest expense	0	0	0	0
Provision (credit)	0	0	0	0
Non-interest income	2,014	1,843	4,017	3,712
Non-interest Expense	1,152	1,020	2,188	1,964
Income before income taxes	864	824	1,833	1,750
Income tax expense	337	321	714	682
Net income	527	503	1,119	1,068
Assets	$ 13,676	$ 11,601	$ 13,676	$ 11,601