Description of Business and Summary of Significant Accounting Policies - Narrative (Detail) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2021 USD ($) segment paymentPlan shares	Dec. 31, 2020 USD ($) shares	Dec. 31, 2019 shares
Organization And Summary Of Significant Accounting Policies [Line Items]
Number of reportable segments | segment	2
Number of payment plans | paymentPlan	2
Guarantee liability	$ 77
Restricted stock units outstanding to purchase shares included in diluted earnings per common share (in shares) | shares	2	2	2
Operating lease liability	$ 27,062
Operating lease right-of-use assets	$ 27,883	$ 22,531
Non-Network Internal-Use Software | Minimum
Organization And Summary Of Significant Accounting Policies [Line Items]
Useful life for finite-lived intangible assets, years	5 years
Non-Network Internal-Use Software | Maximum
Organization And Summary Of Significant Accounting Policies [Line Items]
Useful life for finite-lived intangible assets, years	7 years
Fixed Term Plan
Organization And Summary Of Significant Accounting Policies [Line Items]
Contract term	24 months
Device Payment Plan | Minimum
Organization And Summary Of Significant Accounting Policies [Line Items]
Contract term	24 months
Device Payment Plan | Maximum
Organization And Summary Of Significant Accounting Policies [Line Items]
Contract term	30 months