INCOME TAXES - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets:
NOL carryforwards	$ 158,727	$ 124,877
Stock-based compensation	33,613	35,991
Long-term lease liabilities	32,642
Other	26,226	14,786
Total deferred tax assets	251,208	175,654
Less valuation allowance	(71,472)	(58,903)
Net deferred tax assets	179,736	116,751
Deferred tax liabilities:
Intangible assets	(63,900)	(75,722)
Right-of-use assets	(24,836)
Capitalized software, leasehold improvements and equipment	(12,377)	(3,432)
Capitalized costs to obtain a contract with a customer	(9,400)
Other	(83)	(568)
Total deferred tax liabilities	(110,596)	(79,722)
Net deferred tax assets	$ 69,140	$ 37,029