Corporate Investments and Funds Held For Clients (Classification Of Corporate Investments On The Consolidated Balance Sheets) (Details) - USD ($) $ in Millions		Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019
Corporate Investments And Funds Held For Clients [Abstract]
Cash and cash equivalents		$ 1,705.0	$ 1,949.2	$ 1,826.2
Short-term marketable securities		3.2	10.5
Long-term marketable securities	[1]	0.0	261.4
Total corporate investments		$ 1,708.2	$ 2,221.1

[1] (a) - Long-term marketable securities are included within Other assets on the Consolidated Balance Sheets.