Revenue from Contracts with Customers (Tables)

12 Months Ended

Dec. 31, 2020

Revenue from Contract with Customer [Abstract]

Postpaid service revenues, including postpaid phone revenues and postpaid other revenues, were as follows:


	Year Ended December 31,
(in millions)		2020		2019		2018
Postpaid service revenues

Postpaid phone revenues		$	33,939	$	21,329	$	19,745
Postpaid other revenues		2,367		1,344		1,117

Total postpaid service revenues		$	36,306	$	22,673	$	20,862

Equipment revenues from the lease of mobile communication devices were as follows:


	Year Ended December 31,
(in millions)		2020		2019		2018
Equipment revenues from the lease of mobile communication devices		$	4,181	$	599	$	692

Schedule of Contract Liability and Receivable Balances

The opening and closing balances of our contract asset and contract liability balances from contracts with customers as of December 31, 2019 and December 31, 2020, were as follows:


(in millions)	Contract Assets		Contract Liabilities

Balance as of December 31, 2019	$	63	$	560
Balance as of December 31, 2020	278		824

Change	$	215	$	264

Revenues for the years ended December 31, 2020 and 2019, include the following:


	Year Ended December 31,
(in millions)		2020		2019
Amounts included in the beginning of year contract liability balance		$	545	$	643