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, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2015
Earnings Per Share [Abstract]
Net earnings	$ 187.1	$ 75.9	$ 30.1	$ 33.7	$ 170.1	$ 63.7	$ 40.2	$ 33.5	$ 326.8	$ 307.5	$ 287.1
Basic Weighted-average shares outstanding (in shares)									118.0	118.3	119.9
Basic EPS (in dollars per share)	$ 1.60	$ 0.64	$ 0.25	$ 0.28	$ 1.44	$ 0.54	$ 0.34	$ 0.28	$ 2.77	$ 2.60	$ 2.39