GOODWILL, OTHER INTANGIBLE ASSETS AND MORTGAGE SERVICING RIGHTS (Mortgage Servicing Rights) (Details) - USD ($) $ in Thousands		3 Months Ended				12 Months Ended
		Mar. 31, 2016		Mar. 31, 2015		Dec. 31, 2015
Servicing Asset at Amortized Value, Balance [Roll Forward]
Additions—acquired through business combinations		$ 0		$ 2,172
Valuation adjustments in the period		0				$ 0
Mortgage Servicing Rights [Member]
Morgage Servicing Rights at Amortized Value [Line Items]
Loans Serviced For Others		1,910,000				1,860,000
Custodial Accounts		6,900				8,700
Servicing Asset at Amortized Value, Balance [Roll Forward]
Balance, net of valuation allowance, beginning of the period		13,295		9,030		9,030
Additions—amounts capitalized		1,204		1,216
Amortization	[1]	(823)		(709)
Balance, net of valuation allowance, end of the period		13,676	[2]	$ 11,709	[2]	$ 13,295
Valuation allowance, end of period	[2]	$ 0

[1] 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.

[2] There was no valuation allowance as of March 31, 2016 and 2015.