Earnings Per Share - Computation of Basic EPS (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2018
Earnings Per Share [Abstract]
Net earnings	$ 229.7	$ 166.8	$ 10.1	$ 55.9	$ 183.2	$ 172.2	$ 49.9	$ 76.7	$ 462.5	$ 482.1	$ 427.9
Basic Weighted-average shares outstanding (in shares)									114.7	115.9	116.8
Basic EPS (in dollars per share)	$ 2.00	$ 1.46	$ 0.09	$ 0.49	$ 1.59	$ 1.49	$ 0.43	$ 0.66	$ 4.03	$ 4.16	$ 3.66