Income Taxes - Deferred Tax Valuation Allowances (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Mar. 31, 2023
Deferred Tax Assets, Valuation Allowance [Roll Forward]
Beginning balance	$ 341.6	$ 152.2	$ 362.8
Changes in valuation allowance	302.7	4.2	(2.3)
Ending balance	686.6	341.6	152.2
Lions Gate Entertainment Corp.
Deferred Tax Assets, Valuation Allowance [Roll Forward]
Beginning balance	808.3	455.7	362.8
Changes in valuation allowance	745.8	196.3	87.2
Other	35.0	156.3	5.7
Ending balance	1,589.1	808.3	$ 455.7
Valuation allowance, opening balance from acquisition of eOne	$ 23.0	$ 187.0