Fair Value Measurements - Schedule of Carrying Values and Fair Values of Company’s Outstanding Debt, Film Related Obligations, and Interest Rate Swaps (Details) - USD ($) $ in Millions	Jun. 30, 2025	Mar. 31, 2025
Carrying Value \| Revolving Credit Facility \| Revolving Credit Facility
Fair Value, Carrying Values and Fair Values of Assets and Liabilities Not Required to be Carried at Fair Value on a Recurring Basis [Line Items]
Lines of credit, fair value disclosure	$ 5.3	$ 0.0
Carrying Value \| Term Loan A \| Term Loan A
Fair Value, Carrying Values and Fair Values of Assets and Liabilities Not Required to be Carried at Fair Value on a Recurring Basis [Line Items]
Loans, fair value disclosure	0.0	313.4
Carrying Value \| Exchange Notes \| Senior Notes
Fair Value, Carrying Values and Fair Values of Assets and Liabilities Not Required to be Carried at Fair Value on a Recurring Basis [Line Items]
Senior notes fair value disclosure	382.0	381.6
Carrying Value \| Line of Credit \| eOne IP Credit Facility
Fair Value, Carrying Values and Fair Values of Assets and Liabilities Not Required to be Carried at Fair Value on a Recurring Basis [Line Items]
Lines of credit, fair value disclosure	309.4	317.6
Carrying Value \| Line of Credit \| LG IP Credit Facility
Fair Value, Carrying Values and Fair Values of Assets and Liabilities Not Required to be Carried at Fair Value on a Recurring Basis [Line Items]
Lines of credit, fair value disclosure	938.7	962.9
Carrying Value \| Line of Credit \| 3 Arts Credit Facility
Fair Value, Carrying Values and Fair Values of Assets and Liabilities Not Required to be Carried at Fair Value on a Recurring Basis [Line Items]
Lines of credit, fair value disclosure	30.0	0.0
Carrying Value \| Line of Credit \| Production Tax Credit Facility
Fair Value, Carrying Values and Fair Values of Assets and Liabilities Not Required to be Carried at Fair Value on a Recurring Basis [Line Items]
Lines of credit, fair value disclosure	281.3	276.2
Carrying Value \| Production Loans \| Production Loans
Fair Value, Carrying Values and Fair Values of Assets and Liabilities Not Required to be Carried at Fair Value on a Recurring Basis [Line Items]
Loans, fair value disclosure	1,395.1	1,393.9
Carrying Value \| Secured Debt \| Backlog Facility and Other
Fair Value, Carrying Values and Fair Values of Assets and Liabilities Not Required to be Carried at Fair Value on a Recurring Basis [Line Items]
Backlog Facility and Other, IP credit facility and financing component of interest rate swaps, fair value disclosure	318.4	238.4
Carrying Value \| Secured Debt \| Film Library Facility
Fair Value, Carrying Values and Fair Values of Assets and Liabilities Not Required to be Carried at Fair Value on a Recurring Basis [Line Items]
Backlog Facility and Other, IP credit facility and financing component of interest rate swaps, fair value disclosure	65.5	74.4
Fair Value \| Fair Value (Level 2) \| Revolving Credit Facility \| Revolving Credit Facility
Fair Value, Carrying Values and Fair Values of Assets and Liabilities Not Required to be Carried at Fair Value on a Recurring Basis [Line Items]
Lines of credit, fair value disclosure	20.0	0.0
Fair Value \| Fair Value (Level 2) \| Term Loan A \| Term Loan A
Fair Value, Carrying Values and Fair Values of Assets and Liabilities Not Required to be Carried at Fair Value on a Recurring Basis [Line Items]
Loans, fair value disclosure	0.0	312.9
Fair Value \| Fair Value (Level 2) \| Exchange Notes \| Senior Notes
Fair Value, Carrying Values and Fair Values of Assets and Liabilities Not Required to be Carried at Fair Value on a Recurring Basis [Line Items]
Senior notes fair value disclosure	338.2	360.9
Fair Value \| Fair Value (Level 2) \| Line of Credit \| eOne IP Credit Facility
Fair Value, Carrying Values and Fair Values of Assets and Liabilities Not Required to be Carried at Fair Value on a Recurring Basis [Line Items]
Lines of credit, fair value disclosure	314.5	323.0
Fair Value \| Fair Value (Level 2) \| Line of Credit \| LG IP Credit Facility
Fair Value, Carrying Values and Fair Values of Assets and Liabilities Not Required to be Carried at Fair Value on a Recurring Basis [Line Items]
Lines of credit, fair value disclosure	953.8	978.8
Fair Value \| Fair Value (Level 2) \| Line of Credit \| 3 Arts Credit Facility
Fair Value, Carrying Values and Fair Values of Assets and Liabilities Not Required to be Carried at Fair Value on a Recurring Basis [Line Items]
Lines of credit, fair value disclosure	30.1	0.0
Fair Value \| Fair Value (Level 2) \| Line of Credit \| Production Tax Credit Facility
Fair Value, Carrying Values and Fair Values of Assets and Liabilities Not Required to be Carried at Fair Value on a Recurring Basis [Line Items]
Lines of credit, fair value disclosure	284.9	280.0
Fair Value \| Fair Value (Level 2) \| Production Loans \| Production Loans
Fair Value, Carrying Values and Fair Values of Assets and Liabilities Not Required to be Carried at Fair Value on a Recurring Basis [Line Items]
Loans, fair value disclosure	1,397.7	1,395.4
Fair Value \| Fair Value (Level 2) \| Secured Debt \| Backlog Facility and Other
Fair Value, Carrying Values and Fair Values of Assets and Liabilities Not Required to be Carried at Fair Value on a Recurring Basis [Line Items]
Backlog Facility and Other, IP credit facility and financing component of interest rate swaps, fair value disclosure	321.8	238.9
Fair Value \| Fair Value (Level 2) \| Secured Debt \| Film Library Facility
Fair Value, Carrying Values and Fair Values of Assets and Liabilities Not Required to be Carried at Fair Value on a Recurring Basis [Line Items]
Backlog Facility and Other, IP credit facility and financing component of interest rate swaps, fair value disclosure	$ 66.9	$ 75.9