Income Taxes (Schedule of Income Tax Expense (Benefit)) (Details) - USD ($) $ in Millions	12 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2017
Current
Federal	$ (29.8)	$ 1.8	$ 62.2
State	(2.8)	1.2	0.4
Foreign	0.6	0.2	0.0
Current	(32.0)	3.2	62.6
Deferred
Federal	42.0	(129.9)	33.0
State	1.6	3.2	5.8
Foreign	(0.1)	(0.1)	0.0
Deferred	43.5	(126.8)	38.8
Income tax expense (benefit)	$ 11.5	$ (123.6)	$ 101.4