Goodwill and Intangible Assets - Goodwill (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Sep. 30, 2024	Sep. 30, 2022	Mar. 31, 2025	Mar. 31, 2024	Mar. 31, 2023
Goodwill [Roll Forward]
Goodwill, beginning balance			$ 811.2	$ 795.6
Acquisition of eOne				5.8
Measurement period adjustments			(2.7)	9.8
Goodwill, ending balance			808.5	811.2	$ 795.6
Adjustment to purchase price related to settlement of certain working capital items			12.0	0.0	0.0
Lions Gate Entertainment Corp.
Goodwill [Roll Forward]
Goodwill, beginning balance			811.2	1,289.5
Acquisition of eOne				5.8
Impairment	$ (493.9)	$ (1,475.0)		(493.9)
Measurement period adjustments			(2.7)	9.8
Goodwill, ending balance			808.5	811.2	1,289.5
Adjustment to purchase price related to settlement of certain working capital items			12.0	0.0	0.0
eOne
Goodwill [Roll Forward]
Measurement period adjustments			2.7	(9.8)
Decrease to accounts receivable			5.6	11.4
Decrease to other assets			(4.2)	12.4
Decrease to content related payables			(3.4)	1.9
Decrease to accrued liabilities				3.8
Decrease to participation and residuals			(1.0)	1.9
Decrease to deferred revenue				2.4
eOne | Lions Gate Entertainment Corp.
Goodwill [Roll Forward]
Measurement period adjustments			2.7	(9.8)
Decrease to accounts receivable			5.6	11.4
Decrease to other assets			(4.2)	12.4
Increase to investment in film and television programs			(1.6)	4.0
Decrease to content related payables			(3.4)	1.9
Decrease to accrued liabilities			(1.9)	3.8
Decrease to participation and residuals			(1.0)	1.9
Decrease to deferred revenue				2.4
Motion Picture
Goodwill [Roll Forward]
Goodwill, beginning balance			398.6	393.7
Acquisition of eOne				1.0
Measurement period adjustments			(1.7)	3.9
Goodwill, ending balance			396.9	398.6	393.7
Motion Picture | Lions Gate Entertainment Corp.
Goodwill [Roll Forward]
Goodwill, beginning balance			398.6	393.7
Acquisition of eOne				1.0
Impairment				0.0
Measurement period adjustments			(1.7)	3.9
Goodwill, ending balance			396.9	398.6	393.7
Television Production
Goodwill [Roll Forward]
Goodwill, beginning balance			412.6	401.9
Acquisition of eOne				4.8
Measurement period adjustments			(1.0)	5.9
Goodwill, ending balance			411.6	412.6	401.9
Television Production | Lions Gate Entertainment Corp.
Goodwill [Roll Forward]
Goodwill, beginning balance			412.6	401.9
Acquisition of eOne				4.8
Impairment				0.0
Measurement period adjustments			(1.0)	5.9
Goodwill, ending balance			411.6	412.6	401.9
Media Networks | Lions Gate Entertainment Corp.
Goodwill [Roll Forward]
Goodwill, beginning balance			0.0	493.9
Acquisition of eOne				0.0
Impairment				(493.9)
Measurement period adjustments			0.0	0.0
Goodwill, ending balance			0.0	0.0	$ 493.9
Accumulated goodwill impairment losses			$ 1,969.0	$ 1,969.0