Goodwill, Spectrum Licenses and Intangible Assets (Goodwill and Licenses) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012	Apr. 30, 2013 MetroPCS [Member]
Indefinite-lived Intangible Assets [Line Items]
Goodwill	$ 1,683	$ 0	$ 1,683
Spectrum licenses	18,414	14,550
Acquired spectrum licenses			$ 3,818