LOANS - Narrative (Details) - USD ($)	9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchased loan pools	$ 465,200,000		$ 568,300,000
Purchased loan pools principal balance	459,100,000		559,400,000
Purchased pool loans unamortized purchase premium	6,100,000		8,900,000
Allowance for loan and lease losses, purchased loan pools	1,500,000		1,800,000
Loans modified that are not troubled debt restructurings	36,600,000	$ 58,200,000
Troubled debt restructurings excluding purchased loans	14,200,000		18,200,000
Troubled debt restructurings, previous charge-offs, excluding purchased loans	2,800,000		1,200,000
Allowance for loan losses allocated to troubled debt restructurings, excluding purchased loans	1,200,000		3,100,000
Consumer Installment Home Improvement Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable, net amount	148,000,000		60,800,000
Commercial Insurance Premium Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable, net amount	487,900,000		353,900,000
Purchased Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchased loans, carrying value	917,100,000		1,070,000,000
Purchased loan pools, troubled debt restructuring amount	915,000		925,000
Nonaccrual loans	19,049,000	23,827,000	22,966,000
Troubled debt restructuring loans	20,205,000	21,117,000	23,543,000
Troubled debt restructurings, previous charge-offs, excluding purchased loans	1,500,000		1,500,000
Troubled debt restructurings principal balances	1,000,000	1,900,000
Financing receivable, modifications, subsequent default, recorded investment	2,300,000	733,000
Troubled debt restructuring	26,000,000		28,100,000
Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	15,325,000	16,570,000	18,114,000
Troubled debt restructuring loans	12,452,000	14,013,000	14,209,000
Troubled debt restructurings principal balances	783,000	2,900,000
Financing receivable, modifications, subsequent default, recorded investment	1,200,000	793,000
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	$ 500,000