INCOME TAXES - Income Tax Expense Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2018	Jan. 31, 2017
Federal corporate income tax rate (as percent)	21.00%	21.00%	34.00%	35.00%
Computed expected income tax benefit (expense)	$ 10,030	$ (9,916)	$ (38,078)
State income taxes, net of federal tax effect	81	683	(5,042)
Elimination of net operating loss benefit	(7,239)
Utilization of net operating loss carryforward		1,730
Bad debt loss	6,205
Foreign tax rate differential	(722)	86	(301)
Goodwill impairment losses	(763)	(266)	(168)
Stock options	210	32	962
Domestic production activities deduction			3,204
Other permanent differences, net	(599)	(1,319)	(973)
Federal research and development tax credits		13,866
Adjustments and other differences	(150)	(245)	117
Income tax benefit (expense)	7,053	4,651	$ (40,279)
Research and development state tax credit	2,800
Deferred tax valuation allowance	11,588	$ 5,194
Total income tax benefit	6,800
UK
Deferred tax valuation allowance	$ 7,100