Quarterly report pursuant to Section 13 or 15(d)

Service Revenue (Summary of Changes in Deferred Revenue Related to Material Right Performance Obligations) (Details)

v3.20.1
Service Revenue (Summary of Changes in Deferred Revenue Related to Material Right Performance Obligations) (Details) - USD ($)
$ in Millions
3 Months Ended 9 Months Ended
Feb. 29, 2020
Feb. 28, 2019
Feb. 29, 2020
Feb. 28, 2019
Service Revenue [Abstract]        
Balance, beginning of period $ 45.1 $ 46.0 $ 45.7 $ 46.4
Deferral of revenue 7.4 7.7 20.3 20.9
Recognition of unearned revenue (7.4) (7.6) (20.9) (21.2)
Balance, end of period $ 45.1 $ 46.1 $ 45.1 $ 46.1