CenturyLink Merger - Consideration (Details) - USD ($) $ in Millions		10 Months Ended	12 Months Ended
	Nov. 01, 2017	Oct. 31, 2018	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2017
Business Acquisition [Line Items]
Goodwill			$ 11,119	$ 7,415	$ 10,837
Purchase accounting and other adjustments			$ 340
CenturyLink | Level 3 Parent, LLC
Business Acquisition [Line Items]
Cash, accounts receivable and other current assets		$ 3,291			3,317
Cash, accounts receivable and other current assets, purchase price adjustments		(26)
Property, plant and equipment		9,468			9,311
Property, plant and equipment, purchase price adjustments		157
Other non-current assets		998			782
Other noncurrent assets, purchase price adjustments		216
Current liabilities, excluding the current portion of long-term debt		(1,493)			(1,461)
Current liabilities, excluding current maturities of long-term debt, purchase price adjustments		(32)
Current maturities of long-term debt		(7)			(7)
Current maturities of long-term debt, purchase price adjustments		0
Long-term debt		(10,888)			(10,888)
Long-term debt, purchase price adjustments		0
Deferred revenue and other liabilities		(1,727)			(1,613)
Deferred revenue and other liabilities, purchase price adjustments		(114)
Goodwill		11,177			10,837
Purchase accounting and other adjustments		340
Total estimated aggregate consideration		19,628			19,633
Total estimated aggregate consideration, purchase price adjustments		(5)
Accounts receivable contractual value	$ 884
Acquired finite-lived intangible assets, weighted average useful life	12 years
CenturyLink | Level 3 Parent, LLC | Customer relationships
Business Acquisition [Line Items]
Identifiable intangible assets		8,431			8,964
Identifiable intangible assets, purchase price adjustments		(533)
CenturyLink | Level 3 Parent, LLC | Other
Business Acquisition [Line Items]
Identifiable intangible assets		378			$ 391
Identifiable intangible assets, purchase price adjustments		$ (13)