Service Revenue (Narrative) (Details) - USD ($) $ in Millions	9 Months Ended
	Feb. 28, 2022	Feb. 28, 2021
Service Revenue [Line Items]
Notice of termination period	30 days
Revenue performance obligations	$ 46.1
Revenue performance obligations timing	the Company defers revenue associated with these set-up fees and recognizes it over the period in which such clients are expected to benefit from the material right, which is approximately three to four years
Impairment loss	$ 0.0	$ 0.0
Minimum [Member]
Service Revenue [Line Items]
Revenue performance obligations timing, years	3 years
Maximum [Member]
Service Revenue [Line Items]
Revenue performance obligations timing, years	4 years