Condensed Consolidated Statement 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
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect adjustment for adoption of Accounting Standards Update 2014-09	$ 0.4						$ 1.0	$ (0.6)
Beginning balance at Jun. 30, 2017	996.0				$ 39.4	$ 5.1	54.8	915.7				$ (19.0)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	33.4							33.4
Other comprehensive loss, net of income taxes	0.6											0.6
Shares issued under incentive plans, net of forfeitures	12.0				0.5		11.5
Purchases of Company stock	(17.7)				(0.3)		(17.4)
Share-based compensation	6.7						6.7
Dividends paid		$ (20.9)	$ (2.7)						$ (20.9)	$ (2.7)
Ending balance at Sep. 30, 2017	1,007.8				39.6	5.1	56.6	924.9				(18.4)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect adjustment for adoption of Accounting Standards Update 2014-09	2.4						0.0	2.4
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)