Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Restricted stock units	Common Stock	Common Stock Restricted stock units	Additional paid in capital	Additional paid in capital Restricted stock units	Accumulated deficit	Accumulated other comprehensive income (loss)	Treasury Stock
Beginning Balance, Shares at May. 31, 2020			38,448,536,000
Beginning Balance at May. 31, 2020	$ 454,872		$ 374		$ 561,871		$ (100,318)	$ (1,341)	$ (5,714)
Beginning Balance, Treasury Shares at May. 31, 2020									(370,000,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(4,268)						(4,268)
Issuance/Cancellation of performance share units and restricted stock units, net, Shares				164,946,000
Issuance/Cancellation of performance share units and restricted stock units		$ (143)				$ (143)
Purchase of common stock under ESPP, Shares			79,596,000
Purchases of common stock under ESPP	634		$ 1		633
Stock-based compensation	1,864				1,864
Other comprehensive income, net of tax	2,095							2,095
Ending Balance, Shares at Aug. 31, 2020			38,693,078,000
Ending Balance at Aug. 31, 2020	455,054		$ 375		564,225		(104,586)	754	$ (5,714)
Ending Balance, Treasury Shares at Aug. 31, 2020									(370,000,000)
Beginning Balance, Shares at May. 31, 2020			38,448,536,000
Beginning Balance at May. 31, 2020	454,872		$ 374		561,871		(100,318)	(1,341)	$ (5,714)
Beginning Balance, Treasury Shares at May. 31, 2020									(370,000,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(8,536)
Ending Balance, Shares at Nov. 30, 2020			38,702,030,000
Ending Balance at Nov. 30, 2020	454,343		$ 375		566,602		(108,854)	1,934	$ (5,714)
Ending Balance, Treasury Shares at Nov. 30, 2020									(370,000,000)
Beginning Balance, Shares at Aug. 31, 2020			38,693,078,000
Beginning Balance at Aug. 31, 2020	455,054		$ 375		564,225		(104,586)	754	$ (5,714)
Beginning Balance, Treasury Shares at Aug. 31, 2020									(370,000,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(4,268)						(4,268)
Issuance/Cancellation of performance share units and restricted stock units, net, Shares				8,952,000
Issuance/Cancellation of performance share units and restricted stock units		(10)				(10)
Stock-based compensation	2,387				2,387
Other comprehensive income, net of tax	1,180							1,180
Ending Balance, Shares at Nov. 30, 2020			38,702,030,000
Ending Balance at Nov. 30, 2020	454,343		$ 375		566,602		(108,854)	1,934	$ (5,714)
Ending Balance, Treasury Shares at Nov. 30, 2020									(370,000,000)
Beginning Balance, Shares at May. 31, 2021			38,920,951,000
Beginning Balance at May. 31, 2021	$ 439,457		$ 377		573,507		(131,866)	3,153	$ (5,714)
Beginning Balance, Treasury Shares at May. 31, 2021	(370,000)								(370,000,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	$ (6,972)						(6,972)
Exercise of stock options, Shares			80,635,000
Exercise of stock options	1,280		$ 1		1,279
Issuance/Cancellation of performance share units and restricted stock units, net, Shares			59,371,000	279,495,000
Issuance/Cancellation of performance share units and restricted stock units		(1,734)				(1,734)
Purchase of common stock under ESPP, Shares			49,789,000
Purchases of common stock under ESPP	900		$ 1		899
Stock-based compensation	2,429				2,429
Other comprehensive income, net of tax	590							590
Ending Balance, Shares at Aug. 31, 2021			39,390,241,000
Ending Balance at Aug. 31, 2021	435,950		$ 379		576,380		(138,838)	3,743	$ (5,714)
Ending Balance, Treasury Shares at Aug. 31, 2021									(370,000,000)
Beginning Balance, Shares at May. 31, 2021			38,920,951,000
Beginning Balance at May. 31, 2021	$ 439,457		$ 377		573,507		(131,866)	3,153	$ (5,714)
Beginning Balance, Treasury Shares at May. 31, 2021	(370,000)								(370,000,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	$ (15,323)
Ending Balance, Shares at Nov. 30, 2021			39,455,193,000
Ending Balance at Nov. 30, 2021	$ 432,368		$ 379		580,330		(147,189)	4,562	$ (5,714)
Ending Balance, Treasury Shares at Nov. 30, 2021	(370,000)								(370,000,000)
Beginning Balance, Shares at Aug. 31, 2021			39,390,241,000
Beginning Balance at Aug. 31, 2021	$ 435,950		$ 379		576,380		(138,838)	3,743	$ (5,714)
Beginning Balance, Treasury Shares at Aug. 31, 2021									(370,000,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(8,351)
Exercise of stock options, Shares			56,064,000
Exercise of stock options	1,022				1,022
Issuance/Cancellation of performance share units and restricted stock units, net, Shares				8,695,000
Issuance/Cancellation of performance share units and restricted stock units		$ (83)				$ (83)
Purchase of common stock under ESPP, Shares			193,000
Purchases of common stock under ESPP	3				3
Stock-based compensation	3,008				3,008
Other comprehensive income, net of tax	819							819
Ending Balance, Shares at Nov. 30, 2021			39,455,193,000
Ending Balance at Nov. 30, 2021	$ 432,368		$ 379		$ 580,330		$ (147,189)	$ 4,562	$ (5,714)
Ending Balance, Treasury Shares at Nov. 30, 2021	(370,000)								(370,000,000)