COMMITMENTS AND CONTINGENCIES - Lease Expense Components (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Fixed operating lease costs	$ 20,432	$ 15,125
Variable operating lease costs	3,508	5,724
Short term lease costs	388	1,856
Sublease income	(2,625)	(1,437)
Amortization of finance lease right-of-use assets	0	1,054
Total lease costs	$ 21,703	$ 22,322