Intangible Assets (Tables)

9 Months Ended

Dec. 31, 2015

Goodwill and Intangible Assets Disclosure [Abstract]

Indefinite-Lived Intangible Assets

	March 31, 2015		Net Additions		December 31, 2015
	(in millions)
FCC licenses	$	35,952	$	65	$	36,017
Trademarks	4,035		—		4,035
Goodwill	6,575		—		6,575
	$	46,562	$	65	$	46,627

Intangible Assets Subject to Amortization

		December 31, 2015							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	$	(3,755	)	$	3,168	$	6,923	$	(2,791	)	$	4,132
Other intangible assets:
Favorable spectrum leases	23 years	884		(103		)	781		884		(71		)	813
Favorable tower leases	3 to 7 years	589		(269		)	320		589		(189		)	400
Trademarks	34 years	520		(39		)	481		520		(27		)	493
Other	4 to 10 years	81		(24		)	57		72		(17		)	55
Total other intangible assets		2,074		(435		)	1,639		2,065		(304		)	1,761
Total definite-lived intangible assets		$	8,997	$	(4,190	)	$	4,807	$	8,988	$	(3,095	)	$	5,893