Amount of contribution received by defined benefit plan from employer which increases plan assets.

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

Pension and Postretirement Benefit Plans - Narrative (Details) - Funded - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2021
Qualified and Non-qualified Pension Benefits
Benefit Plan Information
Company contributions year to date	$ 46
Postretirement Benefits
Benefit Plan Information
Company contributions year to date	$ 1
Forecast \| Qualified and Non-qualified Pension Benefits \| Maximum
Benefit Plan Information
Estimated pension and postretirement employer contributions in current fiscal year		$ 200