Goodwill (Details) $ in Millions	6 Months Ended
	Sep. 30, 2018 USD ($)
Goodwill [Roll Forward]
Balance as of March 31, 2018	$ 2,740.8
Business acquisitions	92.0	[1]
Measurement period adjustments	0.7	[1]
Balance as of September 30, 2018	2,833.5
Motion Picture
Goodwill [Roll Forward]
Balance as of March 31, 2018	393.7
Business acquisitions	0.0	[1]
Measurement period adjustments	0.0	[1]
Balance as of September 30, 2018	393.7
Television Production
Goodwill [Roll Forward]
Balance as of March 31, 2018	309.2
Business acquisitions	92.0	[1]
Measurement period adjustments	0.7	[1]
Balance as of September 30, 2018	401.9
Media Networks
Goodwill [Roll Forward]
Balance as of March 31, 2018	2,037.9
Business acquisitions	0.0	[1]
Measurement period adjustments	0.0	[1]
Balance as of September 30, 2018	$ 2,037.9

[1] Represents the goodwill and measurement period adjustments resulting from the acquisition of 3 Arts Entertainment (see Note 2). Measurement period adjustments represented a decrease to the fair value of finite-lived intangible assets and a corresponding increase to goodwill.