Quarterly report pursuant to Section 13 or 15(d)

Accumulated Other Comprehensive (Loss)/Income (Changes in Accumulated Other Comprehensive (Loss)/Income) (Details)

v3.10.0.1
Accumulated Other Comprehensive (Loss)/Income (Changes in Accumulated Other Comprehensive (Loss)/Income) (Details) - USD ($)
$ in Millions
3 Months Ended 6 Months Ended
Nov. 30, 2018
Nov. 30, 2017
Nov. 30, 2018
Nov. 30, 2017
Accumulated Other Comprehensive (Loss)/Income [Abstract]        
Beginning balance $ (35.8) $ 24.4 $ (36.2) [1] $ 20.0
Unrealized losses on available-for-sale securities, net of tax (7.2) (33.6) (5.2) (29.3)
Foreign currency translation adjustment (4.4) (6.0) 0.1
Total other comprehensive loss, net of tax (11.6) (33.6) [2] (11.2) (29.2) [2]
Ending balance (47.4) (9.2) (47.4) (9.2)
Total tax benefit included in other comprehensive loss $ (1.8) $ (19.3) $ (2.3) $ (16.8)
[1] Amounts have been adjusted to reflect the adoption of ASC Topic 606.
[2] Amounts have been adjusted to reflect the adoption of Accounting Standards Codification ("ASC") Topic 606, "Revenue from Contracts with Customers" ("ASC Topic 606").