Intangible Assets (Indefinite-Lived Intangible Assets) (Details) (Successor [Member], USD $) In Millions, unless otherwise specified	3 Months Ended				12 Months Ended		15 Months Ended
	Mar. 31, 2015	Jun. 30, 2014	Mar. 31, 2014		Mar. 31, 2015		Mar. 31, 2014	Dec. 31, 2013
Indefinite-lived Intangible Assets [Line Items]
FCC licenses and trademarks, beginning balance		$ 41,978			$ 41,978
FCC licenses and trademarks, ending balance	39,987		41,978		39,987		41,978
Goodwill, beginning balance		6,383	6,434		6,383
Goodwill, period increase (decrease)	232	40	(51)	[1]	192	[2]
Goodwill, ending balance	6,575		6,383		6,575		6,383
Total indefinite-lived intangible assets including FCC licenses, Trademarks, Goodwill, beginning balance		48,361	48,258		48,361
Indefinite lived intangible assets period increase decrease					(1,799)		103
Total indefinite-lived intangible assets including FCC licenses, Trademarks, Goodwill, ending balance	46,562		48,361		46,562		48,361
FCC Licenses [Member]
Indefinite-lived Intangible Assets [Line Items]
FCC licenses and trademarks, beginning balance		36,043			36,043			35,889
FCC licenses and trademarks, period increase (decrease)					(91)		154
FCC licenses and trademarks, ending balance	35,952		36,043		35,952		36,043	35,889
Trademarks [Member]
Indefinite-lived Intangible Assets [Line Items]
FCC licenses and trademarks, beginning balance		5,935			5,935			5,935
FCC licenses and trademarks, period increase (decrease)							0
Impairment of intangible assets, indefinite-lived (excluding goodwill)					(1,900)	[3]
FCC licenses and trademarks, ending balance	$ 4,035		$ 5,935		$ 4,035		$ 5,935	$ 5,935

[1] Net reduction to goodwill for the Successor three-month transition period ended March 31, 2014 of $51 million was the result of purchase price allocation adjustments associated with the SoftBank Merger.

[2] Net additions to goodwill for the Successor year ended March 31, 2015 of approximately $192 million were the result of purchase price allocation adjustments, which consisted of a $232 million increase recorded during the three-month period ended March 31, 2015 to correct the amount of net deferred tax liabilities recognized in connection with the SoftBank Merger and Clearwire Acquisition and a net $40 million decrease recorded during the three-months ended June 30, 2014, which is also associated with the SoftBank Merger and Clearwire Acquisition.

[3] Net reduction to trademarks for the year ended March 31, 2015 of approximately $1.9 billion was related to the impairment of the Sprint trade name. See discussion below.