Revenue Recognition (Notes)

12 Months Ended

Dec. 31, 2019

Disaggregated revenue from contracts with purchasers. Revenues on sales of oil, NGL, gas and purchased oil and gas are recognized when control of the product is transferred to the purchaser and payment can be reasonably assured. Sales prices for oil, NGL and gas production are negotiated based on factors normally considered in the industry, such as an index or spot price, distance from the well to the pipeline or market, commodity quality and prevailing supply and demand conditions. As such, the prices of oil, NGL and gas generally fluctuate based on the relevant market index rates.

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


	Year Ended December 31,
	2019		2018
	(in millions)
Oil sales	$	4,168	$	3,991
NGL sales	510		695
Gas sales	238		305
Total oil and gas sales	4,916		4,991
Sales of purchased oil	4,726		4,339
Sales of purchased gas	29		49
Total sales of purchased oil and gas	4,755		4,388
Total revenue from contracts with purchasers	$	9,671	$	9,379

Performance obligations and contract balances. The majority of the Company's product sale commitments are short-term in nature with a contract term of one year or less. The Company typically satisfies its performance obligations upon transfer of control as described above in Disaggregated revenue from contracts with purchasers and records the related revenue in the month production is delivered to the purchaser. Settlement statements for sales of oil, NGL and gas and sales of purchased oil and gas may not be received for 30 to 60 days after the date the volumes are delivered, and as a result, the Company is required to estimate the amount of volumes delivered to the purchaser and the price that will be received for the sale of the product. The Company records the differences between estimates and the actual amounts received for product sales in the month that payment is received from the purchaser. As of December 31, 2019 and 2018, the accounts receivable balance representing amounts due or billable under the terms of contracts with purchasers was $968 million and $646 million, respectively.