Capital Stock - Schedule of Stock Option, SARs, Restricted Stock and Restricted Share Unit Activity (Details) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Mar. 31, 2025 USD ($) $ / shares shares
Old Lions Gate Class A Voting Shares | Share-based Payment Arrangement, Options and Stock Appreciation Rights (SARS)
Number of Shares
Outstanding, beginning balance (in shares)	2.4
Granted (in shares)	0.0
Options exercised or restricted stock or RSUs vested (in shares)	0.0
Forfeited or expired (in shares)	(0.1)
Outstanding, ending balance (in shares)	2.3
Weighted-Average Exercise Price
Outstanding, beginning balance (in USD per share) | $ / shares	$ 22,960,000
Granted, weighted average exercise price (in USD per share) | $ / shares	0
Options exercised or restricted stock or RSUs vested, weighted average exercise price (in USD per share) | $ / shares	0
Forfeited or expired, weighted average exercise price (in USD per share) | $ / shares	20,260,000
Outstanding, ending balance (in USD per share) | $ / shares	$ 23,100,000
Weighted-Average Grant-Date Fair Value
Number of shares, vested or expected to vest (in shares)	2.3
Weighted average exercise price, vested or expected to vest (in dollars per share) | $ / shares	$ 23,100,000
Weighted average remaining contractual term, outstanding	1 year 6 months 3 days
Intrinsic value, outstanding | $	$ 0.1
Aggregate intrinsic value, vested and expected to vest | $	$ 0.1
Number of shares exercisable, (in shares)	2.3
Weighted average exercise price (in dollars per share) | $ / shares	$ 23,100,000
Weighted average remaining contractual term, exercisable	1 year 6 months 3 days
Intrinsic value, exercisable | $	$ 0.1
Old Lions Gate Class A Voting Shares | Restricted Stock and Restricted Share Units (RSUs)
Number of Shares
Outstanding, beginning balance (in shares)	0.1
Granted (in shares)	0.1
Options exercised or restricted stock or RSUs vested (in shares)	(0.1)
Forfeited or expired (in shares)	0.0
Outstanding, ending balance (in shares)	0.1
Weighted-Average Grant-Date Fair Value
Outstanding, beginning balance (in USD per share) | $ / shares	$ 9.27
Granted, weighted average grant date fair value (in USD per share) | $ / shares	8.20
Options exercised or restricted stock or RSUs vested, weighted average grant-date fair value (in USD per share) | $ / shares	9.20
Forfeited or expired, weighted average grant-date fair value (in USD per share) | $ / shares	0
Outstanding, ending balance (in USD per share) | $ / shares	$ 8.39
Old Lions Gate Class B Non-Voting Shares | Share-based Payment Arrangement, Options and Stock Appreciation Rights (SARS)
Number of Shares
Outstanding, beginning balance (in shares)	17.1
Granted (in shares)	0.0
Options exercised or restricted stock or RSUs vested (in shares)	0.1
Forfeited or expired (in shares)	(2.2)
Outstanding, ending balance (in shares)	14.8
Weighted-Average Exercise Price
Outstanding, beginning balance (in USD per share) | $ / shares	$ 13,920,000
Granted, weighted average exercise price (in USD per share) | $ / shares	7,120,000
Options exercised or restricted stock or RSUs vested, weighted average exercise price (in USD per share) | $ / shares	5,500,000
Forfeited or expired, weighted average exercise price (in USD per share) | $ / shares	14,640,000
Outstanding, ending balance (in USD per share) | $ / shares	$ 13,860,000
Weighted-Average Grant-Date Fair Value
Number of shares, vested or expected to vest (in shares)	14.8
Weighted average exercise price, vested or expected to vest (in dollars per share) | $ / shares	$ 13,870,000
Weighted average remaining contractual term, outstanding	4 years 2 months 19 days
Intrinsic value, outstanding | $	$ 0.6
Weighted average remaining contractual term, vested and expected to vest	4 years 2 months 15 days
Aggregate intrinsic value, vested and expected to vest | $	$ 0.6
Number of shares exercisable, (in shares)	14.5
Weighted average exercise price (in dollars per share) | $ / shares	$ 13,980,000
Weighted average remaining contractual term, exercisable	4 years 1 month 20 days
Intrinsic value, exercisable | $	$ 0.6
Old Lions Gate Class B Non-Voting Shares | Share-based Payment Arrangement, Options and Stock Appreciation Rights (SARS) | Maximum
Number of Shares
Granted (in shares)	0.1
Old Lions Gate Class B Non-Voting Shares | Restricted Stock and Restricted Share Units (RSUs)
Number of Shares
Outstanding, beginning balance (in shares)	9.8
Granted (in shares)	8.2
Options exercised or restricted stock or RSUs vested (in shares)	(5.9)
Forfeited or expired (in shares)	(1.0)
Outstanding, ending balance (in shares)	11.1
Weighted-Average Grant-Date Fair Value
Outstanding, beginning balance (in USD per share) | $ / shares	$ 8.93
Granted, weighted average grant date fair value (in USD per share) | $ / shares	7.98
Options exercised or restricted stock or RSUs vested, weighted average grant-date fair value (in USD per share) | $ / shares	8.83
Forfeited or expired, weighted average grant-date fair value (in USD per share) | $ / shares	8.32
Outstanding, ending balance (in USD per share) | $ / shares	$ 8.17