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Acquisitions, Divestitures and Exchanges (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2016	Jun. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Mar. 31, 2016	Feb. 29, 2016
Acquisitions
Cash paid for acquisitions and licenses				$ 46	$ 286
Federal Communications Commission deposit		$ 143		143
Exchanges
Assets held for sale	$ 16			16
Cash received from divestitures and exchanges				20	314
Gain on license sales and exchanges	7		$ 24	16	$ 147
License exchange 1
Exchanges
Assets held for sale	8			8
Net cash to be received (paid)							$ 28
License exchange 1, first closing
Exchanges
Cash received from divestitures and exchanges		13
Gain on license sales and exchanges		9
License exchange 2
Exchanges
Cash received from divestitures and exchanges	2
Carrying value of licenses disposed of in exchange	7
Gain on license sales and exchanges	7
License exchange 3
Exchanges
Assets held for sale	8			8
Net cash to be received (paid)						$ (1)
License Acquisitions \| Aggregate license acquisitions
Acquisitions
License acquisition agreement amount	$ 56			$ 56
Cash paid for acquisitions and licenses		$ 46