Intangible Assets (Indefinite-Lived Intangible Assets) (Details) - USD ($) $ in Millions		12 Months Ended
		Mar. 31, 2017		Mar. 31, 2016
Indefinite-lived Intangible Assets [Line Items]
FCC licenses and trademarks, beginning balance		$ 40,073
FCC licenses and trademarks, ending balance		40,585		$ 40,073
Goodwill, beginning balance		6,575		6,575
Goodwill, period increase (decrease)		4	[1]	0
Goodwill, ending balance		6,579		6,575
Total indefinite-lived intangible assets including FCC licenses, Trademarks, Goodwill, beginning balance		46,648		46,562
Indefinite lived intangible assets period increase decrease		516		86
Total indefinite-lived intangible assets including FCC licenses, Trademarks, Goodwill, ending balance		47,164		46,648
FCC Licenses [Member]
Indefinite-lived Intangible Assets [Line Items]
FCC licenses and trademarks, beginning balance		36,038		35,952
FCC licenses and trademarks, period increase (decrease)		512		86
FCC licenses and trademarks, ending balance		36,550		36,038
Trademarks [Member]
Indefinite-lived Intangible Assets [Line Items]
FCC licenses and trademarks, beginning balance		4,035		4,035
FCC licenses and trademarks, period increase (decrease)				0
Impairment of intangible assets, indefinite-lived (excluding goodwill)	[2]	0
FCC licenses and trademarks, ending balance		$ 4,035		$ 4,035

[1] .

[2] .