Planned Divestiture of the Latin American and ILEC Businesses - Additional Information (Details) - USD ($) $ in Millions			12 Months Ended
	Aug. 03, 2021	Jul. 25, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Depreciation and amortization			$ 4,019	$ 4,710	$ 4,829
Disposal Group, Held-for-sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Assumed indebtedness from disposal of business			2,257
Depreciation and amortization			272
Estimated loss on disposal			0
Disposal Group, Held-for-sale, Not Discontinued Operations | Latin American Business
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Assumed indebtedness from disposal of business			435
Disposal Group, Held-for-sale, Not Discontinued Operations | Latin American Business | Level 3 Parent, LLC
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash consideration from disposal of business		$ 2,700
Working capital, other purchase price adjustments and transaction expenses		$ 50
Disposal Group, Held-for-sale, Not Discontinued Operations | ILEC Business
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash consideration from disposal of business	$ 7,500
Assumed indebtedness from disposal of business	1,400		$ 1,822
Purchaser's transaction expenses	$ 1,700