Intangible Assets (Tables)

6 Months Ended

Sep. 30, 2015

Goodwill and Intangible Assets Disclosure [Abstract]

Indefinite-Lived Intangible Assets

	March 31, 2015		Net Additions		September 30, 2015
	(in millions)
FCC licenses	$	35,952	$	38	$	35,990
Trademarks	4,035		—		4,035
Goodwill	6,575		—		6,575
	$	46,562	$	38	$	46,600

Intangible Assets Subject to Amortization

		September 30, 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	$	(3,449	)	$	3,474	$	6,923	$	(2,791	)	$	4,132
Other intangible assets:
Favorable spectrum leases	23 years	884		(91		)	793		884		(71		)	813
Favorable tower leases	3 to 7 years	589		(242		)	347		589		(189		)	400
Trademarks	34 years	520		(35		)	485		520		(27		)	493
Other	4 to 10 years	78		(22		)	56		72		(17		)	55
Total other intangible assets		2,071		(390		)	1,681		2,065		(304		)	1,761
Total definite-lived intangible assets		$	8,994	$	(3,839	)	$	5,155	$	8,988	$	(3,095	)	$	5,893