LOANS AND ALLOWANCE FOR LOAN AND LEASE LOSSES - PCI RECONCILIATION OF LOANS (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018	Dec. 31, 2017
Disclosures on loans acquired
Contractually receivable			$ 4,052,694	$ 4,014,673
Carrying value of loans			4,052,500	4,014,034
PCI loan
Disclosures on loans acquired
Contractually receivable			5,319	5,435
Non-accretable amount			(1,691)	(1,691)
Accretable amount	$ (140)	$ (3,600)	(140)	(140)
Carrying value of loans			$ 3,488	$ 3,604
Rollforward of the accretable discount on PCI loans
Balance at the beginning of the period	(140)	(3,600)
Transfers between non-accretable and accretable	0	90
Net accretion into interest income on loans, including loan fees	0	101
Balance at the end of the period	$ (140)	$ (3,409)