Revenue Recognition (Tables)

3 Months Ended

Mar. 31, 2019

Revenue from Contract with Customer [Abstract]

Disaggregation of revenue

Disaggregated revenue from contracts with purchasers by product type is as follows:

	Three Months Ended March 31,
	2019		2018
	(in millions)
Oil sales	$	917	$	1,013
NGL sales	138		165
Gas sales	80		88
Total oil and gas sales	1,135		1,266
Sales of purchased oil	1,107		1,051
Sales of purchased gas	2		19
Total sales of purchased oil and gas	1,109		1,070
Total revenue derived from contracts with purchasers	$	2,244	$	2,336