GOODWILL, OTHER INTANGIBLE ASSETS AND MORTGAGE SERVICING RIGHTS (Mortgage Servicing Rights) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017		Dec. 31, 2016		Dec. 31, 2015
Servicing Asset at Amortized Value, Balance [Roll Forward]
Servicing Asset at Amortized Cost, Additions, Acquisitions		$ 0		$ 0		$ 2,172
Servicing Asset at Amortized Cost, Additions		94		0		0
Serviced Loans
Servicing Assets at Amortized Value [Line Items]
Loans serviced for others		2,190,000		2,050,000
Mortgage Servicing Rights
Servicing Assets at Amortized Value [Line Items]
Custodial accounts		10,200		10,300
Servicing Asset at Amortized Value, Balance [Roll Forward]
Balance, beginning of the year		15,249	[1]	13,295	[1]	9,030
Amounts capitalized		3,361		5,965		5,313
Amortization	[2]	(3,966)		(4,011)		(3,220)
Valuation adjustments in the period		0
Balance, end of the year	[1]	14,738		$ 15,249		13,295
Valuation Allowance		$ 0				$ 0

[1] no valuation allowance

[2] Amortization of mortgage servicing rights is recorded as a reduction of loan servicing income and any unamortized balance is fully written off if the loan repays in full.