Supplemental Oil and Gas Information (Narrative) (Details) MMBbls in Millions		12 Months Ended
		Dec. 31, 2018 $ / bbl $ / Mcf MMcf	Dec. 31, 2017 $ / bbl $ / Mcf ft³ MMBbls	Dec. 31, 2018 bbl	Dec. 31, 2018 ft³		Dec. 31, 2018 MMBbls		Dec. 31, 2018 $ / Mcf	Dec. 31, 2018	Dec. 31, 2016 ft³ MMBbls	Dec. 31, 2015 ft³ MMBbls
Reserve Quantities [Line Items]
Proved reserves			328.1				432.5	[1]			329.0	456.2
Future net cash flows annual discount factor, percentage										10.00%
U.S. statutory rate		21.00%	35.00%
Equity Method Investee [Member]
Reserve Quantities [Line Items]
Reserves attributable to investees accounted for my the equity method | bbl				0
Crude Oil And Condensate [Member]
Reserve Quantities [Line Items]
Reserve estimates, average market price | $ / bbl		65.56	51.34
Proved undeveloped reserve development window		5 years
Natural Gas Liquids [Member]
Reserve Quantities [Line Items]
Proved reserves			48.9				54.2	[2]			42.5	36.4
Proved undeveloped reserve development window		5 years
Natural Gas [Member]
Reserve Quantities [Line Items]
Reserve estimates, average market price | $ / Mcf		3.10	2.98
Proved reserves | ft³			1,927,100,000,000		2,143,600,000,000	[3]					1,878,000,000,000	1,688,800,000,000
Proved undeveloped reserve development window		5 years
Alberta, Canada [Member]
Reserve Quantities [Line Items]
Working interest											5.00%
Malaysia [Member] | Crude Oil And Condensate [Member]
Reserve Quantities [Line Items]
Proved reserves							51.7
Malaysia [Member] | Natural Gas Liquids [Member]
Reserve Quantities [Line Items]
Proved reserves			0.3				0.7	[2]			0.5	0.6
Malaysia [Member] | Natural Gas [Member]
Reserve Quantities [Line Items]
Proved reserves		468,200	491,400,000,000		468,200,000,000	[3]					539,700,000,000	546,800,000,000
Malaysia [Member] | Natural Gas [Member] | Held-for-sale [Member]
Reserve Quantities [Line Items]
Proved reserves | ft³					26,100
Expected sales proceeds | $ / Mcf									0.24
Canada [Member] | Natural Gas Liquids [Member]
Reserve Quantities [Line Items]
Proved reserves			5.6				5.9	[2]			5.6	0.4
Canada [Member] | Natural Gas [Member]
Reserve Quantities [Line Items]
Proved reserves | ft³			1,212,400,000,000		1,366,400,000,000	[3]					1,118,900,000,000	909,600,000,000
Canada [Member] | Synthetic Oil [Member]
Reserve Quantities [Line Items]
Proved reserves	[4]										0.0	114.8

[1] Includes total proved reserves of 25.5 MMBO for Total and United States attributable to the noncontrolling interest in MP GOM.

[2] Includes total proved reserves of 1.1 MMBBL for Total and United States attributable to the noncontrolling interest in MP GOM.

[3] Includes total proved reserves of 10.8 BCF for Total and United States attributable to the noncontrolling interest in MP GOM.

[4] All synthetic oil operations were sold in June 2016.