Consolidated Statements of Cash Flows - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating Activities
Net income (loss)		$ 256	$ 151	$ (16)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation, depletion and amortization		928	785	673
Deferred income tax provision (benefit)		89	84	(134)
Provision for impairment of properties and equipment (including certain exploration expenses) and investments		86	73	158
Gain (Loss) on Disposition of Assets		380	(145)	170
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net		(153)	81	3
Derivative, Cost of Hedge Net of Cash Received		12	(237)	4
Amortization of stock-based awards		37	34	32
Loss on extinguishment of debt		47	71	17
Undistributed equity (earnings) losses, net of distributions received		(4)	6	0
Cash provided by (used in) operating assets and liabilities:
Accounts receivable		(62)	(59)	(153)
Inventories		6	(15)	(8)
Other current assets		(5)	2	(8)
Accounts payable		97	17	158
Federal Income Taxes receivable and payable		19	(38)	12
Accrued and other current liabilities		3	(22)	(31)
Increase (Decrease) in Other Accrued Liabilities		(28)	(47)	(53)
Other, including changes in other noncurrent assets and liabilities		3	14	29
Net cash provided by operating activities(a)	[1]	1,257	883	507
Investing Activities(a)
Payments to Acquire Oil and Gas Property and Equipment	[2]	1,357	1,476	1,161
Proceeds from sales of assets		592	682	193
Payments to Acquire Businesses, Gross		0	0	799
Proceeds from joint venture formation		0	0	338
Purchases of or contributions to investments		(18)	(102)	(8)
Proceeds from Equity Method Investment, Distribution, Return of Capital		14	0	0
Other		1	0	1
Net Cash Provided by (Used in) Investing Activities	[1]	(773)	(896)	(1,436)
Financing Activities
Proceeds from common stock		2	10	672
Dividends paid on preferred stock		0	(11)	(15)
Payments related to induced conversion of preferred stock to common stock		(58)	0	0
Borrowings on credit facility		1,541	1,453	661
Payments on credit facility		(1,871)	(1,123)	(661)
Proceeds from long-term debt, net of discount		593	494	148
Payments for retirement of long-term debt, including premium		(594)	(986)	(165)
Taxes paid for shares withheld		16	14	12
Payments for debt issuance costs and credit facility amendment fees		(3)	(10)	(2)
Other		(16)	17	(2)
Net cash provided by (used in) financing activities		(422)	(170)	624
Net increase (decrease) in cash and cash equivalents and restricted cash		62	(183)	(305)
Cash and cash equivalents and restricted cash at beginning of period		18	201	506
Cash and cash equivalents and restricted cash at end of period		80	18	201
Partnership [Member]
Investing Activities(a)
Payments to Acquire Oil and Gas Property and Equipment	[3]	$ 5	$ 0	$ 0

[1] (a) Amounts reflect both continuing and discontinued operations unless otherwise noted.

[2] (b)   Incurred capital expenditures were $1,313 million, $1,510 million and $1,232 million for the respective periods. The difference between incurred and cash
capital expenditures is due to changes in related accounts payable and accounts receivable.

[3] (c) Incurred capital expenditures were $8 million for 2019. The difference between incurred and cash capital expenditures is due to changes in related accounts
payable and accounts receivable.