SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)

12 Months Ended

Dec. 31, 2020

Summary of the activity of capitalized exploratory well costs for continuing operations

The following table summarizes the activity of capitalized exploratory well costs for continuing operations for the years ended December 31:


millions	2020		2019		2018
Balance — beginning of year	$	424	$	112	$	108
Exploratory well costs acquired through the Acquisition	—		231		—
Additions to capitalized exploratory well costs pending the determination of proved reserves	122		383		220
Reclassifications to property, plant and equipment based on the determination of proved reserves	(309)		(230)		(198)
Capitalized exploratory well costs charged to expense	(26)		(72)		(18)
Balance — end of year	$	211	$	424	$	112

Summary of the activity of the asset retirement obligation

The following table summarizes the activity of asset retirement obligations for the years ended December 31:


millions	2020		2019
Beginning balance	$	4,659	$	1,499
Liabilities assumed in the Acquisition	—		3,370
Liabilities incurred – capitalized to PP&E	79		71
Liabilities settled and paid	(186)		(200)
Accretion expense	147		131
Acquisitions, divestitures and other, net	(294)		—
WES loss of control	—		(359)
Revisions to previous estimates	(275)		147
Ending balance (a)	$	4,130	$	4,659

(a)The ending balance included $153 million and $248 million related to the current balance of AROs that are included in Accrued Liabilities on the Consolidated Balance Sheets at December 31, 2020, and 2019, respectively.

Summary of cash equivalents and restricted cash equivalents


millions	December 31, 2020		December 31, 2019
Cash and cash equivalents	$	2,008	$	3,032
Restricted cash and restricted cash equivalents	170		485
Cash and restricted cash included in assets held for sale	—		3
Restricted cash and restricted cash equivalents included in long-term receivables and other assets, net	16		54
Cash, cash equivalents, restricted cash and restricted cash equivalents	$	2,194	$	3,574