LOANS - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchased loan pools	$ 319,600		$ 328,200
Purchased loan pools principal balance	316,200		324,400
Purchased pool loans unamortized purchase premium	3,400		3,800
Allowance for loan and lease losses, purchased loan pools	1,000		1,100
Loans modified that are not troubled debt restructurings	28,600	$ 16,200
Troubled debt restructurings excluding purchased loans	14,700		15,600
Troubled debt restructurings, previous charge-offs, excluding purchased loans	1,100		2,800
Allowance for loan losses allocated to troubled debt restructurings, excluding purchased loans	1,500		1,400
Minimum | Substandard
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	100	100	100
Troubled debt restructuring loans	100	100	100
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
Consumer Installment Home Improvement Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable, net amount	280,300		273,700
Commercial Insurance Premium Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable, net amount	501,900		482,500
Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable, net amount	818,587		861,595
Purchased loans, carrying value	818,600		861,600
Purchased loan pools, troubled debt restructuring amount	902		904
Nonaccrual loans	15,940		15,428
Troubled debt restructurings, previous charge-offs, excluding purchased loans	1,700
Troubled debt restructurings principal balances	186	355
Financing receivable, modifications, subsequent default, recorded investment	906	2,100
Troubled debt restructuring	24,500		24,900
Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	14,420		$ 14,202
Troubled debt restructuring loans	1,155	93
Troubled debt restructurings principal balances	1,200	93
Financing receivable, modifications, subsequent default, recorded investment	$ 3,000	$ 1,600