Wireless Licenses Goodwill and Other Intangible Assets - Additional Information (Detail) (Wireless Licenses, USD $) In Billions, unless otherwise specified	Sep. 30, 2013
Wireless Licenses
Wireless Licenses, Goodwill and Other Intangible Assets [Line Items]
Wireless licenses under development	$ 7.7

Amount of structure or a modification to a structure under construction. Includes recently completed structures or modifications to structures that have not been placed into service.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 360

-SubTopic 10

-Section 50

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229

Name:	us-gaap_ConstructionInProgressGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant