Weighted average rate for present value of future retirement benefits cash flows, used to determine benefit obligation of defined benefit plan.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (k)(1)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

Name:	us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Benefit Plans - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
Benefit Plans - Narrative (Details) - USD ($) $ in Millions	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Mar. 31, 2020	Dec. 31, 2019
Components of net periodic cost
Discount rate	$ (433)	$ (228)	$ (397)	$ (493)
Pension benefits
Components of net periodic cost
Discount rate	2.74%		2.74%		3.37%	3.31%