INCOME TAXES - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Net operating loss carryforwards	$ 45,195	$ 45,639
Deferred revenue	2,514	3,770
Accounts payable and accrued expenses	2,298	2,499
Stock-based compensation	1,876	1,539
Capital loss carryforwards	0	1,288
Tax credit carryforwards	423	423
Deferred rent and other	582	1,529
Foreign deferred assets	1,892	1,251
Business interest carryforwards	22,719	22,946
Gross deferred income tax assets	77,499	80,884
Valuation allowance for deferred income tax assets	(68,567)	(73,495)
Net deferred income tax assets	8,932	7,389
Deferred income tax liabilities:
Deferred contract costs	(6,686)	6,439
Other	(998)	(41)
Deferred tax assets, net	$ 1,248	$ 909