Consolidated Statements of Earnings - 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
Income Statement [Abstract]
Revenues	$ 1,361.9	$ 1,249.9	$ 968.7	$ 948.6	$ 1,211.2	$ 1,224.8	$ 953.4	$ 972.8	$ 4,529.0	$ 4,362.2	$ 4,329.9
Cost of revenues									3,265.1	3,131.9	3,167.4
Selling, general and administrative expenses									639.0	577.5	564.5
Total operating expenses									3,904.1	3,709.5	3,731.8
Operating income	298.8	226.3	26.8	73.1	240.8	233.6	78.2	100.1	624.9	652.7	598.1
Interest expense, net									(58.8)	(41.8)	(38.6)
Other non-operating income (expenses), net									13.4	(3.7)	1.5
Earnings (loss) before income taxes	294.8	210.5	10.5	63.8	230.0	223.6	64.3	89.3	579.5	607.3	561.0
Provision for income taxes									117.0	125.2	133.1
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 earnings per share (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
Diluted earnings per share (in dollars per share)	$ 1.97	$ 1.43	$ 0.09	$ 0.48	$ 1.55	$ 1.45	$ 0.42	$ 0.64	$ 3.95	$ 4.06	$ 3.56
Weighted-average shares outstanding:
Basic (in shares)									114.7	115.9	116.8
Diluted (in shares)									117.0	118.8	120.4