CONSOLIDATED STATEMENTS OF STOCKHOLDER'S EQUITY - USD ($) $ in Millions	Total	COMMON STOCK	RETAINED EARNINGS (ACCUMULATED DEFICIT)	RETAINED EARNINGS (ACCUMULATED DEFICIT) Cumulative Effect, Period of Adoption, Adjustment
Balance at beginning of period at Dec. 31, 2018		$ 10,050	$ (182)	$ 22
Increase (Decrease) in Stockholder's Equity
Net income	$ 1,441		1,441
Dividends declared to Qwest Services Corporation	(1,100)		(1,100)
Balance at end of period at Sep. 30, 2019	10,231	10,050	181
Balance at beginning of period at Dec. 31, 2018		10,050	(182)	22
Balance at end of period at Dec. 31, 2019	$ 10,117	10,050	67	3
Increase (Decrease) in Stockholder's Equity
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member
Balance at beginning of period at Jun. 30, 2019		10,050	104
Increase (Decrease) in Stockholder's Equity
Net income	$ 477		477
Dividends declared to Qwest Services Corporation			(400)
Balance at end of period at Sep. 30, 2019	10,231	10,050	181
Balance at beginning of period at Dec. 31, 2019	$ 10,117	10,050	67	3
Balance at end of period at Jan. 01, 2020				3
Increase (Decrease) in Stockholder's Equity
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member
Balance at beginning of period at Dec. 31, 2019	$ 10,117	10,050	67	$ 3
Increase (Decrease) in Stockholder's Equity
Net income	1,312		1,312
Dividends declared to Qwest Services Corporation	(1,400)		(1,350)
Other			(5)
Balance at end of period at Sep. 30, 2020	10,077	10,050	27
Balance at beginning of period at Jun. 30, 2020		10,050	73
Increase (Decrease) in Stockholder's Equity
Net income	379		379
Dividends declared to Qwest Services Corporation			(425)
Balance at end of period at Sep. 30, 2020	$ 10,077	$ 10,050	$ 27