Fair Value Measurements (Carrying Values And Fair Values Of Assets and Liabilities Not Required to be Carried at Fair Value on a Recurring Basis) (Details) - USD ($) $ in Millions	Sep. 30, 2024	Mar. 31, 2024
Senior Notes | 5.5% 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]
Coupon rate	5.50%
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	$ 417.6	$ 569.9
Carrying Value | Term Loans | 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	312.9	396.6
Carrying Value | Term Loans | Term Loan B
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	249.7	816.9
Carrying Value | Senior Notes | 5.5% 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 and Programming Notes, fair value disclosure	698.2	696.6
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	1,239.4	1,286.2
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	271.9	285.4
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	92.3	107.6
Carrying Value | Secured Debt | 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	334.0	0.0
Carrying Value | Secured Debt | 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	447.9	0.0
Carrying Value | Programming Notes | Programming 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 and Programming Notes, fair value disclosure	67.9	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	259.6	258.7
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	421.5	575.0
Fair Value | Fair Value (Level 2) | Term Loans | 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	312.9	397.3
Fair Value | Fair Value (Level 2) | Term Loans | Term Loan B
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	249.7	818.1
Fair Value | Fair Value (Level 2) | Senior Notes | 5.5% 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 and Programming Notes, fair value disclosure	581.4	536.2
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	1,244.8	1,292.2
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	273.2	287.3
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	94.2	109.9
Fair Value | Fair Value (Level 2) | Secured Debt | 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	340.0	0.0
Fair Value | Fair Value (Level 2) | Secured Debt | 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	455.0	0.0
Fair Value | Fair Value (Level 2) | Programming Notes | Programming 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 and Programming Notes, fair value disclosure	67.9	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	$ 260.0	$ 260.0