Changes in Accumulated Other Comprehensive Income/(Loss) by Component - Summary of Changes in Accumulated Balances for Each Component of Accumulated Other Comprehensive Income/(Loss) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Changes In Accumulated Other Comprehensive Income [Roll Forward]
Stockholders' equity at beginning of period			$ 1,094.3
Stockholders' equity at end of period	$ 1,122.6		1,122.6
Foreign Currency Translation
Changes In Accumulated Other Comprehensive Income [Roll Forward]
Stockholders' equity at beginning of period	(53.3)	$ (30.6)	(43.2)	$ (48.9)
Other comprehensive income/(loss) before reclassifications	(6.1)	(2.4)	(16.1)	15.9
Amounts reclassified from accumulated other comprehensive income/(loss)	0.0	0.0	0.0	0.0
Stockholders' equity at end of period	(59.3)	(33.0)	(59.3)	(33.0)
Available- for-Sale Securities
Changes In Accumulated Other Comprehensive Income [Roll Forward]
Stockholders' equity at beginning of period	0.0	2.6	0.0	2.3
Other comprehensive income/(loss) before reclassifications	0.0	0.8	0.0	1.1
Amounts reclassified from accumulated other comprehensive income/(loss)	0.0	0.0	0.0	0.0
Stockholders' equity at end of period	0.0	3.3	0.0	3.3
Pension and Post- Retirement Liabilities
Changes In Accumulated Other Comprehensive Income [Roll Forward]
Stockholders' equity at beginning of period	(10.2)	(9.0)	(10.2)	(9.2)
Other comprehensive income/(loss) before reclassifications	0.4	0.0	0.4	0.0
Amounts reclassified from accumulated other comprehensive income/(loss)	0.0	0.2	0.0	0.4
Stockholders' equity at end of period	(9.8)	(8.8)	(9.8)	(8.8)
AOCI Attributable to Parent
Changes In Accumulated Other Comprehensive Income [Roll Forward]
Stockholders' equity at beginning of period	(63.5)	(37.1)	(53.5)	(55.8)
Other comprehensive income/(loss) before reclassifications	(5.7)	(1.6)	(15.7)	17.0
Amounts reclassified from accumulated other comprehensive income/(loss)	0.0	0.2	0.0	0.4
Stockholders' equity at end of period	$ (69.2)	$ (38.4)	$ (69.2)	$ (38.4)