LOANS - Narrative (Details)	3 Months Ended		12 Months Ended
	Mar. 31, 2019 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2018 USD ($) loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchased loan pools	$ 253,700,000		$ 262,600,000
Purchased loan pools principal balance	252,000,000		260,500,000
Purchased pool loans unamortized purchase premium	1,700,000		2,100,000
Allowance for loan and lease losses, purchased loan pools	697,000		732,000
Loans modified that are not troubled debt restructurings	26,900,000	$ 28,600,000
Troubled debt restructurings excluding purchased loans	12,900,000		11,000,000
Troubled debt restructurings, previous charge-offs, excluding purchased loans	893,000		890,000
Allowance for loan losses allocated to troubled debt restructurings, excluding purchased loans	728,000		820,000
Minimum | Substandard
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	100,000	100,000	100,000
Troubled debt restructuring loans	100,000	100,000	100,000
Minimum | Independent Third Party Loan Review
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amount of loan relationship subject to sampling for annual review	1,000,000
Consumer Installment Home Improvement Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable, net amount	382,500,000		399,900,000
Commercial Insurance Premium Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable, net amount	487,000,000		413,500,000
Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable, net amount	2,472,271,000		2,588,832,000
Purchased loans, carrying value	2,470,000,000		2,590,000,000
Purchased pool loans, principal balance, nonaccrual status	400,000		$ 0
Purchased loan pools, troubled debt restructuring amount	0
Number of loans accounts as an accruing troubled debt restructuring | loan			0
Nonaccrual loans	23,846,000		$ 24,107,000
Troubled debt restructurings, previous charge-offs, excluding purchased loans	1,100,000		940,000
Troubled debt restructurings principal balances	773,000	186,000
Financing receivable, modifications, subsequent default, recorded investment	831,000	906,000
Troubled debt restructuring	22,300,000		22,200,000
Purchased Loans | 7
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchased loan pools principal balance	400,000
Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	17,633,000		$ 17,952,000
Troubled debt restructuring loans	2,161,000	1,155,000
Troubled debt restructurings principal balances	2,200,000	1,200,000
Financing receivable, modifications, subsequent default, recorded investment	$ 837,000	$ 3,000,000