Background and Summary of Significant Accounting Policies - Summary of Significant Accounting Policies (Details) $ in Millions	12 Months Ended
	Dec. 31, 2021 USD ($) reporting_unit segment	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Statement [Line Items]
Advertising expense	$ 24	$ 25	$ 28
Bank overdrafts	$ 0	0
Accounts receivable, period past due	30 days
Number of reporting units | reporting_unit	1
Number of operating segments | segment	1
Customer relationships
Statement [Line Items]
Finite-lived intangible assets, maximum useful life	10 years
Capitalized software
Statement [Line Items]
Finite-lived intangible assets, maximum useful life	7 years
Qwest Communications International, Inc. | Pension, Supplemental and Other Postretirement Benefit Plans
Statement [Line Items]
Pension settlement term	30 years
Repayments on affiliate obligation	$ 46	71
Qwest Communications International, Inc. | Pension, Supplemental and Other Postretirement Benefit Plans
Statement [Line Items]
Repayments on affiliate obligation	$ 46	$ 71
Minimum
Statement [Line Items]
Contract term	1 year
Customer relationship period for revenue recognition	10 years
Maximum
Statement [Line Items]
Contract term	5 years
Customer relationship period for revenue recognition	20 years
Average | Consumer customers, average contract life
Statement [Line Items]
Customer life	30 months
Average | Business customer, average contract life
Statement [Line Items]
Customer life	29 months