Income Taxes - Components of Deferred Income Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Jun. 30, 2024	Jun. 30, 2023
Deferred tax assets:
Accrued expenses not currently deductible	$ 237.4	$ 209.5
Stock-based compensation expense	51.3	48.8
Foreign tax credits	12.0	13.3
Fixed and intangible assets	194.9	108.2
Net operating losses	41.7	37.5
Prepaid royalty	0.0	18.0
Unrealized investment losses, net	351.4	519.5
Other	39.1	39.9
Deferred tax assets, gross	927.8	994.7
Less: valuation allowances	(11.1)	(18.6)
Deferred tax assets, net	916.7	976.1
Deferred tax liabilities:
Deferred contract costs	620.7	578.1
Prepaid expenses	88.8	78.9
Prepaid retirement benefits	40.3	30.8
Tax on unrepatriated earnings	10.2	10.1
Other	20.8	20.7
Deferred tax liabilities	780.8	718.6
Net deferred tax assets	$ 135.9	$ 257.5