Pension and Other Benefit Plans - Narrative (Details) - USD ($) $ in Millions	6 Months Ended
Sep. 30, 2021	Mar. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Deferred compensation plan, liability	$ 40	$ 42
Directors
Defined Benefit Plan Disclosure [Line Items]
Maximum deferral percentage	100.00%

The carrying amount of the liability as of the balance sheet date to an individual under a deferred compensation arrangement. This amount may be the result of periodic accruals made over the period of active employment, or reflect termination benefits resulting contractual terms or a death benefit.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 710
-SubTopic 10
-Section 30
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6409875&loc=d3e20015-108363

Name:	us-gaap_DeferredCompensationArrangementWithIndividualRecordedLiability
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant