Summary of Significant Accounting Policies - Cumulative Effect of Changes Made on Consolidated Balance Sheet For Adoption of ASU 2020-06 (Detail) - USD ($) $ in Millions	Jun. 30, 2021	Jan. 01, 2021	Dec. 31, 2020
Assets
Property, plant and equipment, net	$ 15,665	$ 12,702	$ 12,747
Liabilities
Current portion of debt and finance leases	1,530	2,182	2,132
Debt and finance leases, net of current portion	7,871	9,775	9,556
Mezzanine equity
Convertible senior notes		0	51
Equity
Additional Paid in Capital		26,786	27,260
Accumulated deficit	$ (3,608)	$ (5,188)	(5,399)
Restatement Adjustment [Member] \| Accounting Standards Update 2020-06 [Member]
Assets
Property, plant and equipment, net			(45)
Liabilities
Current portion of debt and finance leases			50
Debt and finance leases, net of current portion			219
Mezzanine equity
Convertible senior notes			(51)
Equity
Additional Paid in Capital			(474)
Accumulated deficit			$ 211

The cumulative amount of the reporting entity's undistributed earnings or deficit.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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