SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)

12 Months Ended

Dec. 31, 2019

Accounting Policies [Abstract]

Summary of cash equivalents and restricted cash equivalents

The following table provides a reconciliation of cash, cash equivalents, restricted cash and restricted cash equivalents as reported at the end of the period in the Consolidated Statements of Cash Flows for the twelve months ended December 31, 2019 to the line items within the Consolidated Balance Sheet at December 31, 2019. There was no restricted cash or restricted cash equivalents at December 31, 2018.

millions	December 31, 2019
Cash and cash equivalents	$	3,032
Restricted cash and restricted cash equivalents	480
Cash and restricted cash included in assets held for sale	8
Restricted cash and restricted cash equivalents included in long-term receivables and other assets, net	54
Cash, cash equivalents, restricted cash, and restricted cash equivalents	$	3,574

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	2019			2018			2017
Balance — beginning of year	$	112		$	108		$	56
Exploratory well costs acquired through the Acquisition	231			—			—
Additions to capitalized exploratory well costs pending the determination of proved reserves	383			220			201
Reclassifications to property, plant and equipment based on the determination of proved reserves	(230		)	(198		)	(128		)
Capitalized exploratory well costs charged to expense	(72		)	(18		)	(21		)
Balance — end of year	$	424		$	112		$	108

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	2019			2018
Beginning balance	$	1,499		$	1,312
Liabilities assumed in the Acquisition	3,344			—
Liabilities incurred – capitalized to PP&E	131			31
Liabilities settled and paid	(200		)	(40		)
Accretion expense	71			67
Acquisitions, dispositions and other	—			(18		)
WES loss of control	(359		)	—
Revisions to previous estimates	147			147
Ending balance (a)	$	4,633		$	1,499

^(a)  The ending balance included $248 million and $75 million related to the current balance of AROs that are included in Accrued Liabilities on the Consolidated Balance Sheets at December 31, 2019 and 2018, respectively.