Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	12 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2019
Statement of Comprehensive Income [Abstract]
Net earnings (loss)	$ 306.6	$ (234.3)	$ 46.3
Other comprehensive income (loss), net of income taxes
Pension and other postretirement benefit plans activity, net of income taxes	(17.7)	(29.3)	(6.8)
Unrealized foreign currency translation adjustment	21.7	(6.8)	(2.8)
Other comprehensive income (loss), net of income taxes	4.0	(36.1)	(9.6)
Comprehensive income (loss)	$ 310.6	$ (270.4)	$ 36.7