Annual report pursuant to Section 13 and 15(d)

Funds Held for Clients and Corporate Investments (Realized Gains and Losses from Sale of Available-for-sale Securities) (Details)

v3.7.0.1
Funds Held for Clients and Corporate Investments (Realized Gains and Losses from Sale of Available-for-sale Securities) (Details) - USD ($)
$ in Millions
3 Months Ended 12 Months Ended
Aug. 31, 2016
[1]
Feb. 29, 2016
[1]
May 31, 2017
May 31, 2016
May 31, 2015
Funds Held for Clients and Corporate Investments [Abstract]          
Gross realized gains     $ 0.1 $ 0.1 $ 0.3
Gross realized losses    
Net realized gains $ 0.1 $ 0.1 $ 0.1 [1] $ 0.1 [1] $ 0.3
[1] Total net realized gains on the combined funds held for clients and corporate investment portfolios.