Cover - USD ($)	12 Months Ended
	Dec. 31, 2019	Mar. 05, 2020	Jun. 30, 2019
Entity Information [Line Items]
Document Type	10-K
Document Annual Report	true
Document Transition Report	false
Entity File Number	001-03040
Entity Registrant Name	QWEST CORP
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 Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		1
Documents Incorporated by Reference	None.
Entity Central Index Key	0000068622
Document Period End Date	Dec. 31, 2019
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Public Float			$ 0
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
6.125% Notes Due 2053
Entity Information [Line Items]
Title of 12(b) Security	6.125% Notes Due 2053
Trading Symbol	CTY
Security Exchange Name	NYSE
6.875% Notes Due 2054
Entity Information [Line Items]
Title of 12(b) Security	6.875% Notes Due 2054
Trading Symbol	CTV
Security Exchange Name	NYSE
6.625% Notes Due 2055
Entity Information [Line Items]
Title of 12(b) Security	6.625% Notes Due 2055
Trading Symbol	CTZ
Security Exchange Name	NYSE
7.00% Notes Due 2056
Entity Information [Line Items]
Title of 12(b) Security	7.00% Notes Due 2056
Trading Symbol	CTAA
Security Exchange Name	NYSE
6.5% Notes Due 2056
Entity Information [Line Items]
Title of 12(b) Security	6.5% Notes Due 2056
Trading Symbol	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	CTDD
Security Exchange Name	NYSE