Segment Disclosures and Related Information - Net Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Net Income (Loss) Attributable to ConocoPhillips [Abstract]
Consolidated net income (loss) attributable to ConocoPhillips	$ 2,379	$ (450)	$ 5,452	$ (1,929)
Alaska [Member] \| Operating Segments [Member]
Net Income (Loss) Attributable to ConocoPhillips [Abstract]
Consolidated net income (loss) attributable to ConocoPhillips	405	(16)	935	(76)
Lower 48 [Member] \| Operating Segments [Member]
Net Income (Loss) Attributable to ConocoPhillips [Abstract]
Consolidated net income (loss) attributable to ConocoPhillips	1,631	(78)	3,274	(880)
Canada [Member] \| Operating Segments [Member]
Net Income (Loss) Attributable to ConocoPhillips [Abstract]
Consolidated net income (loss) attributable to ConocoPhillips	155	(75)	267	(270)
Europe, Middle East and North Africa [Member] \| Operating Segments [Member]
Net Income (Loss) Attributable to ConocoPhillips [Abstract]
Consolidated net income (loss) attributable to ConocoPhillips	241	92	601	318
Asia Pacific [Member] \| Operating Segments [Member]
Net Income (Loss) Attributable to ConocoPhillips [Abstract]
Consolidated net income (loss) attributable to ConocoPhillips	257	25	749	945
Other International [Member] \| Operating Segments [Member]
Net Income (Loss) Attributable to ConocoPhillips [Abstract]
Consolidated net income (loss) attributable to ConocoPhillips	(97)	(8)	(106)	14
Corporate and Other [Member] \| Corporate, Non-Segment [Member]
Net Income (Loss) Attributable to ConocoPhillips [Abstract]
Consolidated net income (loss) attributable to ConocoPhillips	$ (213)	$ (390)	$ (268)	$ (1,980)