LEASES - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Jan. 01, 2019
Leases [Abstract]
Lessee, Operating Lease, Description	The Company leases real estate properties for its network of bank branches, financial centers and corporate offices.
Lessee, Operating Lease, Option to Extend	Most lease agreements include one or more options to renew, with renewal terms that can extend the original lease term from one to twenty years or more.
Operating Lease, Right-of-Use Asset	$ 75,500	$ 77,700
Operating Lease Liability	82,991	$ 85,100
Operating Lease, Expense	2,900
Cash paid for amounts included in the measurement of lease liabilities	$ 2,200
Weighted average remaining lease term	10 years 9 months 18 days
Weighted average discount rate	3.31%
Minimum [Member]
Lessee, Operating Lease, Renewal Term	1 year
Maximum [Member]
Lessee, Operating Lease, Renewal Term	20 years