LEASES - Supplemental Balance Sheet Information (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($)
Assets
Operating lease right-of-use assets, Impact of ASC 842 Transition	$ 0
Operating lease right-of-use assets, As of March 31, 2019	70,851
Liabilities
Short-term operating lease liability, Impact of ASC 842 Transition	0
Short-term operating lease liability, As of March 31, 2019	17,660
Long-term operating lease liability, Impact of ASC 842 Transition	0
Long-term operating lease liability. As of March 31, 2019	52,993
Total operating lease liabilities, As of March 31, 2019	70,653
Impact of ASC 842 Transition
Assets
Leases commenced during the quarter	2,935
Payments, amortization and terminations	(4,763)
Liabilities
Leases commenced during the quarter	678
Payments, amortization and terminations	(1,780)
Leases commenced during the quarter	2,256
Payments, amortization and terminations	(2,917)
Leases commenced during the quarter	2,934
Payments, amortization and terminations	$ (4,697)