Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130543-203045

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130539-203045

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130545-203045

Name:	us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Segment Reporting Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Energy Segment
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 1,687	$ 1,914	$ 3,173	$ 3,451
Automotive Segment
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	744	737	1,437	1,423
Petroleum products \| Energy Segment
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,549	1,821	2,943	3,278
Nitrogen fertilizer products \| Energy Segment
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	138	93	230	173
Automotive services \| Automotive Segment
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	345	334	672	651
Aftermarket parts sales \| Automotive Segment
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 399	$ 403	$ 765	$ 772