Summary of Significant Accounting Policies - Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	May 31, 2022	May 31, 2021	May 31, 2020
Accounting Policies [Abstract]
Contract assets	$ 0	$ 0
Contract liabilities	0	0
Revenue	266	0
Revenue recognized previously included in contract liabilities	0	0	$ 0
Revenue from performance obligations satisfied in previous periods	$ 0	$ 0	$ 0