Consolidated Statements Of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Cash flows from operating activities:
Net income (loss)	$ 178	$ (42)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depletion, depreciation and amortization	357	337
Impairment of oil and gas properties	0	285
Exploration expenses, including dry holes	7	10
Deferred income taxes	50	(31)
Gain on disposition of assets, net	(4)	(11)
Accretion of discount on asset retirement obligations	4	5
Interest expense	1	1
Derivative related activity	136	(141)
Amortization of stock-based compensation	17	22
Other	20	25
Change in operating assets and liabilities:
Accounts receivable	(181)	92
Inventories	(6)	(19)
Investments	4	4
Other current assets	(3)	(6)
Accounts payable	(9)	(153)
Interest payable	(21)	(29)
Income taxes payable	1	0
Other current liabilities	3	15
Net cash provided by operating activities	554	364
Cash flows from investing activities:
Proceeds from disposition of assets	4	78
Proceeds from investments	555	458
Purchase of investments	(94)	(315)
Additions to oil and gas properties	(818)	(433)
Additions to other assets and other property and equipment, net	(51)	(86)
Net cash used in investing activities	(404)	(298)
Cash flows from financing activities:
Principal payments on long-term debt	0	(485)
Purchases of treasury stock	(45)	(36)
Net cash used in financing activities	(45)	(521)
Net increase (decrease) in cash and cash equivalents	105	(455)
Cash and cash equivalents, beginning of period	896	1,118
Cash and cash equivalents, end of period	$ 1,001	$ 663