Fair Value of Financial Instruments - Summary of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Millions	Dec. 31, 2018	Jun. 30, 2018
Cash and cash equivalents:
Money market funds	$ 69.8	$ 86.8
Other current assets:
Securities	0.2	0.1
Other non-current assets:
Securities	71.3	66.9
Total assets as of period end	141.3	153.8
Liabilities:
Contingent consideration obligations	17.4	18.6
Total liabilities as of period end	17.4	18.6
Level 1
Cash and cash equivalents:
Money market funds	69.8	86.8
Other current assets:
Securities	0.2	0.1
Other non-current assets:
Securities	71.3	66.9
Total assets as of period end	141.3	153.8
Liabilities:
Contingent consideration obligations	0.0	0.0
Total liabilities as of period end	0.0	0.0
Level 2
Cash and cash equivalents:
Money market funds	0.0	0.0
Other current assets:
Securities	0.0	0.0
Other non-current assets:
Securities	0.0	0.0
Total assets as of period end	0.0	0.0
Liabilities:
Contingent consideration obligations	0.0	0.0
Total liabilities as of period end	0.0	0.0
Level 3
Cash and cash equivalents:
Money market funds	0.0	0.0
Other current assets:
Securities	0.0	0.0
Other non-current assets:
Securities	0.0	0.0
Total assets as of period end	0.0	0.0
Liabilities:
Contingent consideration obligations	17.4	18.6
Total liabilities as of period end	$ 17.4	$ 18.6