Property, Plant and Equipment (Narrative) (Detail) $ in Millions	1 Months Ended
Mar. 31, 2020 USD ($)
Wexpro \| Natural Gas Gathering Systems \| Colorado, Utah and Wyoming
Property Plant And Equipment [Line Items]
Payments to acquire existing natural gas gathering systems	$ 38

The cash outflow to purchase long lived physical asset use for the normal oil and gas operations and not intended for resale.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3213-108585

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