Schedule II - Valuation and Qualifying Accounts (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Allowance for credit losses deducted from accounts receivable:
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	$ 1,507
Charged to Expenses	743	$ 1,390
Charged to Other Accounts	139	165
Deductions	1,238	1,173
Balance at End of Period	1,151	1,507
Allowance for credit losses deducted from accounts receivable: | Adjusted opening balance
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period		1,125
Balance at End of Period			$ 1,125
Allowance for credit losses deducted from accounts receivable: | Long-term device installment plan receivable
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	254
Balance at End of Period	255	254
Allowance for doubtful accounts deducted from accounts receivable:
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period		860	930
Charged to Expenses			1,441
Charged to Other Accounts			133
Deductions			1,644
Balance at End of Period			860
Allowance for doubtful accounts deducted from accounts receivable: | Long-term device installment plan receivable
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period		127
Balance at End of Period			127
Valuation allowance for deferred tax assets:
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	2,183	2,260	2,741
Charged to Expenses	339	202	402
Charged to Other Accounts	0	84	8
Deductions	948	363	891
Balance at End of Period	$ 1,574	$ 2,183	$ 2,260