Intangible Assets (Indefinite-Lived Intangible Assets) (Details) $ in Millions	9 Months Ended
	Dec. 31, 2016 USD ($)
Indefinite-lived Intangible Assets [Line Items]
Indefinite-lived Intangible Assets, Period Start	$ 40,073
Indefinite-lived Intangible Assets, Period End	40,556
Goodwill, beginning balance	6,575
Goodwill, Period Increase (Decrease)	4
Goodwill, ending balance	6,579
Total indefinite-lived intangible assets including FCC licenses, Trademarks, Goodwill, beginning balance	46,648
Indefinite lived intangible assets period increase decrease	487
Total indefinite-lived intangible assets including FCC licenses, Trademarks, Goodwill, ending balance	47,135
FCC Licenses [Member]
Indefinite-lived Intangible Assets [Line Items]
Indefinite-lived Intangible Assets, Period Start	36,038
Indefinite-lived Intangible Assets, Period Increase (Decrease)	483
Indefinite-lived Intangible Assets, Period End	36,521
Indefinite-lived Intangible Assets Acquired	85
Trademarks [Member]
Indefinite-lived Intangible Assets [Line Items]
Indefinite-lived Intangible Assets, Period Start	4,035
Indefinite-lived Intangible Assets, Period Increase (Decrease)	0
Indefinite-lived Intangible Assets, Period End	$ 4,035