DEFERRED CLIENT CONVERSION AND START-UP COSTS - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Jun. 30, 2025	Jun. 30, 2024
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Deferred client conversion and start-up costs	$ 842.9	$ 892.1
Deferred client conversion and start-up costs	837.5	884.5
Other start-up costs	5.4	7.6
Amortization of deferred costs	$ 148.8	$ 132.9