Intangible Assets (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended			0 Months Ended	3 Months Ended	0 Months Ended	3 Months Ended
	Jun. 30, 2014 Successor [Member]		Jun. 30, 2014 FCC Licenses [Member] Successor [Member]	Jul. 10, 2013 SoftBank Merger [Member] Successor [Member]	Jun. 30, 2014 SoftBank Merger [Member] Successor [Member]	Jul. 08, 2013 Clearwire Acquisition [Member]	Jun. 30, 2014 Clearwire Acquisition [Member] Successor [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Assets Held-for-sale, Current			$ 300
Goodwill, Period Increase (Decrease)	(40)	[1]			44		4
Payments directly attributable to performance under report and order, net change related to FCC licenses	38
Goodwill, Acquired During Period				$ 6,343		$ 437

[1] Net reduction to goodwill for the Successor three-month period ended June 30, 2014 of approximately $40 million was the result of purchase price allocation adjustments, which consisted of a $44 million reduction associated with the SoftBank Merger and a $4 million addition associated with the Clearwire Acquisition.