SUMMARY OF SIGNIFICANT ACCOUNTING AND REPORTING POLICIES (Details)	12 Months Ended
	Dec. 31, 2018 USD ($) banking_offices segment	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Organization and Basis of Presentation [Abstract]
Number of branches | banking_offices	59
Number of branches in grocery stores | banking_offices	15
Segment Information [Abstract]
Number of reportable segments | segment	1
Cash and Cash Equivalents [Abstract]
Cash on deposit with the Federal Reserve required to meet regulatory reserve and clearing requirements	$ 34,100,000	$ 32,200,000
Goodwill and Other Intangible Assets [Abstract]
Goodwill impairment loss	0	0
Amortization expense of intangible assets	5,213,000	1,955,000	$ 1,940,000
Core deposit intangible
Goodwill and Other Intangible Assets [Abstract]
Intangible assets, net	13,100,000
Amortization expense of intangible assets			$ 1,800,000
Trust relationship intangible
Goodwill and Other Intangible Assets [Abstract]
Intangible assets, net	4,500,000
Core Deposit Intangible and Trust Relationship Intangible [Member]
Goodwill and Other Intangible Assets [Abstract]
Amortization expense of intangible assets	$ 5,100,000	$ 1,800,000
Premises | Minimum
Premises and Equipment [Abstract]
Estimated useful life	15 years
Premises | Maximum
Premises and Equipment [Abstract]
Estimated useful life	40 years
Equipment | Minimum
Premises and Equipment [Abstract]
Estimated useful life	3 years
Equipment | Maximum
Premises and Equipment [Abstract]
Estimated useful life	10 years