Long-Term Debt - Additional Information (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Debt Disclosure [Abstract]
Debt, outstanding note	$ 14,500	$ 14,600
Debt, discounts and premiums	19	18
Unamortized debt issuance costs	31	33
Additions for mark-to-market adjustments on hedged debt	$ 534	$ 402

Amount, after accumulated amortization, of debt discount (premium).

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant