Wireless Licenses, Goodwill and Other Intangible Assets - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Indefinite-lived Intangible Assets [Line Items]
Gain (loss) on disposition of licenses, pre-tax	$ (1,195)	$ 0
Wireless Licenses
Indefinite-lived Intangible Assets [Line Items]
Wireless licenses under development	3,500	7,200
Interest costs capitalized	64	$ 88
Assets held-for-sale	$ 2,800
Average remaining renewal period of wireless license portfolio (in years)	4 years 6 months
Spectrum Licenses, 39 GHz
Indefinite-lived Intangible Assets [Line Items]
Gain (loss) on disposition of licenses, pre-tax	$ (1,200)
Gain (loss) on disposition of licenses	(914)
Disposal Group, Held-for-sale, Not Discontinued Operations | Spectrum licenses
Indefinite-lived Intangible Assets [Line Items]
Intangible assets held-for-sale	$ 1,600