Goodwill, Customer Relationships and Other Intangible Assets - Additional Information (Details)			3 Months Ended		6 Months Ended		12 Months Ended
	Jan. 31, 2021 USD ($)	Jan. 01, 2021 USD ($)	Jun. 30, 2021 USD ($) $ / shares	Jun. 30, 2020 USD ($) $ / shares	Jun. 30, 2021 USD ($) segment $ / shares	Jun. 30, 2020 USD ($) $ / shares	Dec. 31, 2021 USD ($) $ / shares
Goodwill and Intangible Assets Disclosure [Abstract]
Number of reportable segments | segment					2
Number of operating segments | segment					2
Impairment loss	$ 0
Intangible assets, gross (including goodwill)			$ 41,700,000,000		$ 41,700,000,000
Change in Accounting Estimate [Line Items]
Amortization of intangible assets			318,000,000	$ 440,000,000	743,000,000	$ 871,000,000
Net income			$ (506,000,000)	$ (377,000,000)	$ (981,000,000)	$ (691,000,000)
Basic earnings per common share (in dollars per share) | $ / shares			$ (0.47)	$ (0.35)	$ (0.90)	$ (0.64)
Diluted earnings per common share (in dollars per share) | $ / shares			$ (0.46)	$ (0.35)	$ (0.90)	$ (0.64)
Reclassification of intangible assets
Change in Accounting Estimate [Line Items]
Amortization of intangible assets			$ 7,000,000		$ 15,000,000
Net income			$ 5,000,000		$ 11,000,000
Basic earnings per common share (in dollars per share) | $ / shares					$ 0.01
Diluted earnings per common share (in dollars per share) | $ / shares					$ 0.01
Reclassification of intangible assets | Forecast
Change in Accounting Estimate [Line Items]
Amortization of intangible assets							$ 30,000,000
Net income							$ 23,000,000
Basic earnings per common share (in dollars per share) | $ / shares							$ 0.02
Diluted earnings per common share (in dollars per share) | $ / shares							$ 0.02
Reclassification of intangible assets | Right-of-way
Change in Accounting Estimate [Line Items]
Finite-lived intangible assets		$ 268,000,000
Remaining amortization period		9 years