Intangible Assets (Tables)

12 Months Ended

Mar. 31, 2016

Goodwill and Intangible Assets Disclosure [Abstract]

Indefinite-Lived Intangible Assets

The following provides the activity of Indefinite-lived intangible assets within the consolidated balance sheets:

	March 31, 2015		Net Additions		March 31, 2016
	(in millions)
FCC licenses	$	35,952	$	86	$	36,038
Trademarks	4,035		—		4,035
Goodwill	6,575		—		6,575
	$	46,562	$	86	$	46,648

	March 31, 2014		Net Reductions					March 31, 2015
	(in millions)
FCC licenses	$	36,043	$	(91	)			$	35,952
Trademarks	5,935		(1,900		)	(1	)	4,035
Goodwill	6,383		192			(2	)	6,575
	$	48,361	$	(1,799	)			$	46,562

Intangible Assets Subject to Amortization

		March 31, 2016							March 31, 2015
	Useful Lives	Gross Carrying Value		Accumulated Amortization			Net Carrying Value		Gross Carrying Value		Accumulated Amortization			Net Carrying Value
		(in millions)
Customer relationships	4 to 8 years	$	6,923	$	(4,045	)	$	2,878	$	6,923	$	(2,791	)	$	4,132
Other intangible assets:
Favorable spectrum leases	23 years	881		(110		)	771		884		(71		)	813
Favorable tower leases	3 to 7 years	589		(302		)	287		589		(189		)	400
Trademarks	34 years	520		(43		)	477		520		(27		)	493
Other	4 to 10 years	83		(27		)	56		72		(17		)	55
Total other intangible assets		2,073		(482		)	1,591		2,065		(304		)	1,761
Total definite-lived intangible assets		$	8,996	$	(4,527	)	$	4,469	$	8,988	$	(3,095	)	$	5,893

Intangible Assets Subject to Amortization, Future Amortization Expense

	Fiscal Year 2016		Fiscal Year 2017		Fiscal Year 2018		Fiscal Year 2019		Fiscal Year 2020
	(in millions)
Estimated amortization expense	$	1,157	$	882	$	666	$	462	$	257