Condensed Consolidated Statements of Shareholders' Equity - USD ($) $ in Millions	Total	Cumulative Effect, Period of Adoption, Adjustment	Common Stock	Class B Common Stock	Series A Preferred Stock	Common Stock	Common Stock Common Stock	Common Stock Class B Common Stock	Additional Paid-in Capital	Retained Earnings	Retained Earnings Cumulative Effect, Period of Adoption, Adjustment	Retained Earnings Common Stock	Retained Earnings Class B Common Stock	Retained Earnings Series A Preferred Stock	Accumulated Other Comprehensive Income (Loss)
Beginning balance at Jun. 30, 2019	$ 974.6	$ (7.8)					$ 40.1	$ 5.1	$ 216.7	$ 759.0	$ (7.8)				$ (46.3)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings (loss)	6.1									6.1
Other comprehensive income (loss), net of income taxes	(4.4)														(4.4)
Shares issued under incentive plans, net of forfeitures	0.5						0.1		0.4
Purchases of Company stock	(1.8)						(0.1)		(1.7)
Share-based compensation	7.5								7.5
Dividends paid			$ (24.3)	$ (2.9)	$ (14.4)							$ (24.3)	$ (2.9)	$ (14.4)
Accretion of Series A preferred stock					(4.5)									(4.5)
Ending balance at Sep. 30, 2019	928.6						40.1	5.1	222.9	711.2					(50.7)
Beginning balance at Jun. 30, 2019	974.6	(7.8)					40.1	5.1	216.7	759.0	(7.8)				(46.3)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings (loss)	(240.5)
Other comprehensive income (loss), net of income taxes	(3.8)
Ending balance at Mar. 31, 2020	592.1						40.3	5.1	225.2	371.6					(50.1)
Beginning balance at Jun. 30, 2019	$ 974.6	(7.8)					40.1	5.1	216.7	759.0	(7.8)				(46.3)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member
Ending balance at Jun. 30, 2020	$ 388.2	2.1					40.3	5.1	227.6	197.6	2.1				(82.4)
Beginning balance at Sep. 30, 2019	928.6						40.1	5.1	222.9	711.2					(50.7)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings (loss)	37.8									37.8
Other comprehensive income (loss), net of income taxes	9.6														9.6
Shares issued under incentive plans, net of forfeitures	0.6						0.1		0.5
Purchases of Company stock	(2.4)								(2.4)
Share-based compensation	2.2								2.2
Dividends paid			(24.5)	(3.0)	(14.1)							(24.5)	(3.0)	(14.1)
Accretion of Series A preferred stock					(4.5)									(4.5)
Ending balance at Dec. 31, 2019	930.3						40.2	5.1	223.2	702.9					(41.1)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings (loss)	(284.4)									(284.4)
Other comprehensive income (loss), net of income taxes	(9.0)														(9.0)
Shares issued under incentive plans, net of forfeitures	0.4						0.1		0.3
Purchases of Company stock	(0.5)								(0.5)
Share-based compensation	2.2								2.2
Dividends paid			$ (25.3)	$ (3.0)	(14.0)							$ (25.3)	$ (3.0)	(14.0)
Accretion of Series A preferred stock					$ (4.6)									$ (4.6)
Ending balance at Mar. 31, 2020	592.1						40.3	5.1	225.2	371.6					(50.1)
Beginning balance at Jun. 30, 2020	388.2	2.1					40.3	5.1	227.6	197.6	2.1				(82.4)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings (loss)	42.3									42.3
Other comprehensive income (loss), net of income taxes	7.1														7.1
Shares issued under incentive plans, net of forfeitures	0.4						0.1		0.3
Purchases of Company stock	(0.4)								(0.4)
Share-based compensation	8.8								8.8
Ending balance at Sep. 30, 2020	448.5						40.4	5.1	236.3	242.0					(75.3)
Beginning balance at Jun. 30, 2020	388.2	$ 2.1					40.3	5.1	227.6	197.6	$ 2.1				(82.4)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings (loss)	269.9
Other comprehensive income (loss), net of income taxes	18.1
Ending balance at Mar. 31, 2021	693.9						40.5	5.1	243.0	469.6					(64.3)
Beginning balance at Sep. 30, 2020	448.5						40.4	5.1	236.3	242.0					(75.3)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings (loss)	148.5									148.5
Other comprehensive income (loss), net of income taxes	9.1														9.1
Shares issued under incentive plans, net of forfeitures	0.5						0.2		0.3
Purchases of Company stock	(0.5)					$ (0.1)			(0.4)
Share-based compensation	3.8								3.8
Ending balance at Dec. 31, 2020	609.9						40.5	5.1	240.0	390.5					(66.2)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings (loss)	79.1									79.1
Other comprehensive income (loss), net of income taxes	1.9														1.9
Shares issued under incentive plans, net of forfeitures	0.6						0.0		0.6
Purchases of Company stock	(0.4)								(0.4)
Share-based compensation	2.8								2.8
Ending balance at Mar. 31, 2021	$ 693.9						$ 40.5	$ 5.1	$ 243.0	$ 469.6					$ (64.3)