LOANS - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 2,372,436	$ 1,129,064
Borrower's sustained repayment performance period	6 months
Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 1,169,807	0
Acquired credit impaired	17,000
Certain loans acquired in transfer not accounted for as debt securities, note balance, net	21,700
Financing receivable not considered impaired at time of acquisition	1,150,000
Residential Mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Foreclosed property	363	90
Residential Mortgages | Mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Process of foreclosure	2,000	$ 2,400
Residential Mortgages | Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 636,880