Condensed Consolidated Statements of Shareholders' Equity - USD ($) $ in Millions	Total	Common Stock	Class B Common Stock	Series A Preferred Stock	Common Stock Common Stock	Common Stock Class B Common Stock	Additional Paid-in Capital	Retained Earnings	Retained Earnings Common Stock	Retained Earnings Class B Common Stock	Retained Earnings Series A Preferred Stock	Accumulated Other Comprehensive Loss
Beginning balance at Jun. 30, 2018	$ 1,097.5				$ 39.8	$ 5.1	$ 199.5	$ 889.8				$ (36.7)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	17.0							17.0
Other comprehensive loss, net of income taxes	(1.9)											(1.9)
Shares issued under incentive plans, net of forfeitures	1.1				0.2		0.9
Purchases of Company stock	(3.2)				(0.1)		(3.1)
Share-based compensation	10.2						10.2
Dividends paid		$ (23.0)	$ (2.8)	$ (14.0)					$ (23.0)	$ (2.8)	$ (14.0)
Accretion of Series A preferred stock				(4.3)							(4.3)
Ending balance at Sep. 30, 2018	1,079.0				39.9	5.1	207.5	865.1				(38.6)
Beginning balance at Jun. 30, 2018	1,097.5				39.8	5.1	199.5	889.8				(36.7)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	35.6
Other comprehensive loss, net of income taxes	(4.5)
Ending balance at Dec. 31, 2018	1,055.7				40.0	5.1	212.7	839.1				(41.2)
Beginning balance at Sep. 30, 2018	1,079.0				39.9	5.1	207.5	865.1				(38.6)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	18.6							18.6
Other comprehensive loss, net of income taxes	(2.6)											(2.6)
Shares issued under incentive plans, net of forfeitures	1.4				0.1		1.3
Purchases of Company stock	(1.8)						(1.8)
Share-based compensation	5.7						5.7
Dividends paid		(23.1)	(2.8)	(14.4)					(23.1)	(2.8)	(14.4)
Accretion of Series A preferred stock				(4.3)							(4.3)
Ending balance at Dec. 31, 2018	1,055.7				40.0	5.1	212.7	839.1				(41.2)
Beginning balance at Jun. 30, 2019	974.6				40.1	5.1	216.7	759.0				(46.3)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	6.1							6.1
Other comprehensive 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				40.1	5.1	216.7	759.0				(46.3)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	43.9
Other comprehensive loss, net of income taxes	5.2
Ending balance at Dec. 31, 2019	930.3				40.2	5.1	223.2	702.9				(41.1)
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	37.8							37.8
Other comprehensive 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)				0.0		(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)