Wireless Licenses Goodwill and Other Intangible Assets - Additional Information (Detail) (USD $)	1 Months Ended		3 Months Ended	6 Months Ended
	Jan. 25, 2013 AT&T Amount Expected To Be Received Upon Closing	Jan. 25, 2013 Investment Firm Amount Expected To Be Received Upon Closing	Mar. 31, 2013 License Exchange Transactions	Jun. 30, 2013 Wireless Licenses
Wireless Licenses, Goodwill and Other Intangible Assets [Line Items]
Assets Held-for-sale, Current				$ 2,300,000,000
Acquisitions			500,000,000	43,000,000
License purchase and exchange transactions, net cash proceeds	1,900,000,000	200,000,000
Wireless licenses under development				$ 7,700,000,000