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, 2016	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015
Changes In Accumulated Other Comprehensive Income [Roll Forward]
Stockholders' equity at beginning of period			$ 1,045.5
Other comprehensive income/(loss) before reclassifications	$ (12.2)	$ (5.1)	(23.0)	$ (17.3)
Amounts reclassified from accumulated other comprehensive income/(loss)	0.1	0.1	0.3	0.2
Stockholders' equity at end of period	985.8		985.8
Foreign Currency Translation
Changes In Accumulated Other Comprehensive Income [Roll Forward]
Stockholders' equity at beginning of period	(43.2)	(28.0)	(31.9)	(16.6)
Other comprehensive income/(loss) before reclassifications	(12.0)	(5.4)	(23.2)	(17.0)
Amounts reclassified from accumulated other comprehensive income/(loss)	0.0	0.0	0.0	0.0
Stockholders' equity at end of period	(55.1)	(33.5)	(55.1)	(33.5)
Available-for-Sale Securities
Changes In Accumulated Other Comprehensive Income [Roll Forward]
Stockholders' equity at beginning of period	1.7	1.4	1.3	2.0
Other comprehensive income/(loss) before reclassifications	(0.2)	0.3	0.2	(0.3)
Amounts reclassified from accumulated other comprehensive income/(loss)	0.0	0.0	0.0	0.0
Stockholders' equity at end of period	1.5	1.7	1.5	1.7
Accumulated Defined Benefit Plans Adjustment Attributable to Parent
Changes In Accumulated Other Comprehensive Income [Roll Forward]
Stockholders' equity at beginning of period	(7.5)	(6.3)	(7.6)	(6.3)
Other comprehensive income/(loss) before reclassifications	0.0	0.0	0.0	0.0
Amounts reclassified from accumulated other comprehensive income/(loss)	0.1	0.1	0.3	0.2
Stockholders' equity at end of period	(7.3)	(6.2)	(7.3)	(6.2)
AOCI Attributable to Parent
Changes In Accumulated Other Comprehensive Income [Roll Forward]
Stockholders' equity at beginning of period	(48.9)	(32.9)	(38.2)	(20.9)
Stockholders' equity at end of period	$ (60.9)	$ (38.0)	$ (60.9)	$ (38.0)