Cover - shares	6 Months Ended
	Jun. 30, 2021	Aug. 05, 2021
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Entity File Number	001-03040
Entity Registrant Name	QWEST CORPORATION
Entity Incorporation, State or Country Code	CO
Entity Tax Identification Number	84-0273800
Entity Address, Address Line One	100 CenturyLink Drive,
Entity Address, City or Town	Monroe,
Entity Address, State or Province	LA
Entity Address, Postal Zip Code	71203
City Area Code	318
Local Phone Number	388-9000
Entity Information [Line Items]
Document Period End Date	Jun. 30, 2021
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding (in shares)		1
Entity Central Index Key	0000068622
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q2
Amendment Flag	false
6.5% Notes Due 2056
Entity Information [Line Items]
Title of 12(b) Security	6.5% Notes Due 2056
Trading Symbol(s)	CTBB
Security Exchange Name	NYSE
6.75% Notes Due 2057
Entity Information [Line Items]
Title of 12(b) Security	6.75% Notes Due 2057
Trading Symbol(s)	CTDD
Security Exchange Name	NYSE