LEASES - Maturities of operating lease liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Jan. 01, 2019
Operating Lease Liabilities, Payments Due [Abstract]
One year	$ 11,193
Two years	10,682
Three years	10,147
Four years	10,110
Five years	9,997
Thereafter	48,791
Total undiscounted lease payments	100,920
Less: Present value discount	(17,929)
Lease Liability	$ 82,991	$ 85,100