LOANS AND ALLOWANCE FOR LOAN AND LEASE LOSSES - PCI RECONCILIATION OF LOANS (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Dec. 31, 2018
Disclosures on loans acquired
Contractually receivable			$ 4,297,610	$ 4,147,249
Carrying value of loans			4,298,710	4,148,227
PCI loan
Disclosures on loans acquired
Contractually receivable			3,989	4,251
Non-accretable amount			(1,405)	(1,521)
Accretable amount	$ (50)	$ (140)	(50)	(50)
Carrying value of loans			$ 2,534	$ 2,680
Rollforward of the accretable discount on PCI loans
Balance at the beginning of the period	(50)	(140)
Transfers between non-accretable and accretable	(116)	0
Net accretion into interest income on loans, including loan fees	116	0
Balance at the end of the period	$ (50)	$ (140)