Long-Term and Other Debt - Debt Issuance Costs (Details) - USD ($) $ in Millions	Dec. 31, 2020	Nov. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
Debt Disclosure [Abstract]
Gross financing costs	$ 8	$ 17	$ 16	$ 26

Amount, before accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=124435984&loc=d3e28555-108399

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