Stock-Based Compensation (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Stock-based compensation
Pre-tax compensation expense	$ 30	$ 16
Long-term stock awards
Stock-based compensation
Pre-tax compensation expense	3	4
Stock options
Stock-based compensation
Pre-tax compensation expense	4	3
Restricted stock units
Stock-based compensation
Pre-tax compensation expense	19	8
Performance Restricted Stock Units
Stock-based compensation
Pre-tax compensation expense	2	1
Phantom stock awards
Stock-based compensation
Pre-tax compensation expense	$ 2	$ 0

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5047-113901

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 14.F)
-URI http://asc.fasb.org/extlink&oid=115993241&loc=d3e301413-122809

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(1)(i)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

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