Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Millions	2 Months Ended	10 Months Ended	12 Months Ended
Dec. 31, 2020	Oct. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Actuarial (losses) gains associated with pension and postretirement plans, tax	$ 0	$ 0	$ 0	$ 0
Reclassification of realized losses on pension and postretirement to income, tax	$ 0	$ 0	$ 0	$ 0

Amount of tax expense (benefit) for (increase) decrease in value of benefit obligation for change in actuarial assumptions and increase (decrease) in value of plan assets from experience different from that assumed of defined benefit plan, that has not been recognized in net periodic benefit (cost) credit.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=121641772&loc=d3e640-108580

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