Segment Disclosures and Related Information - Net Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Net Income (Loss) Attributable to ConocoPhillips [Abstract]
Consolidated net income (loss) attributable to ConocoPhillips	$ 2,091	$ 260	$ 3,073	$ (1,479)
Alaska [Member] \| Operating Segments [Member]
Net Income (Loss) Attributable to ConocoPhillips [Abstract]
Consolidated net income (loss) attributable to ConocoPhillips	371	(141)	530	(60)
Lower 48 [Member] \| Operating Segments [Member]
Net Income (Loss) Attributable to ConocoPhillips [Abstract]
Consolidated net income (loss) attributable to ConocoPhillips	1,175	(365)	1,643	(802)
Canada [Member] \| Operating Segments [Member]
Net Income (Loss) Attributable to ConocoPhillips [Abstract]
Consolidated net income (loss) attributable to ConocoPhillips	102	(86)	112	(195)
Europe, Middle East and North Africa [Member] \| Operating Segments [Member]
Net Income (Loss) Attributable to ConocoPhillips [Abstract]
Consolidated net income (loss) attributable to ConocoPhillips	207	25	360	226
Asia Pacific [Member] \| Operating Segments [Member]
Net Income (Loss) Attributable to ConocoPhillips [Abstract]
Consolidated net income (loss) attributable to ConocoPhillips	175	648	492	920
Other International [Member] \| Operating Segments [Member]
Net Income (Loss) Attributable to ConocoPhillips [Abstract]
Consolidated net income (loss) attributable to ConocoPhillips	(5)	(6)	(9)	22
Corporate and Other [Member] \| Corporate, Non-Segment [Member]
Net Income (Loss) Attributable to ConocoPhillips [Abstract]
Consolidated net income (loss) attributable to ConocoPhillips	$ 66	$ 185	$ (55)	$ (1,590)