Consolidated Statements Of Cash Flows (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Cash flows from operating activities:
Net income (loss)	$ (78)	$ 123
Adjustments to reconcile net income to net cash provided by operating activities:
Depletion, depreciation and amortization	310	217
Impairment of oil and gas properties	138	0
Impairment of Inventory and Other Property and Equipment	6	0
Exploration expenses, including dry holes	5	7
Deferred income taxes	(37)	39
Gain on disposition of assets, net	(1)	(6)
Accretion of discount on asset retirement obligations	3	3
Discontinued operations	(3)	103
Interest expense	5	4
Derivative related activity	(35)	86
Amortization of stock-based compensation	22	22
Other	(1)	7
Change in operating assets and liabilities, net of effects from acquisitions and dispositions:
Accounts receivable, net	96	(37)
Income taxes receivable	1	5
Inventories	(34)	(16)
Prepaid expenses	(5)	(1)
Other current assets	(7)	(3)
Accounts payable	(250)	(70)
Interest payable	(20)	(26)
Income taxes payable	0	9
Other current liabilities	(11)	0
Net cash provided by operating activities	104	466
Cash flows from investing activities:
Proceeds from disposition of assets, net of cash sold	4	86
Additions to oil and gas properties	(658)	(664)
Additions to other assets and other property and equipment, net	(63)	(48)
Net cash used in investing activities	(717)	(626)
Cash flows from financing activities:
Borrowings under long-term debt	0	150
Principal payments on long-term debt	0	(100)
Payments of other liabilities	0	(1)
Exercise of long-term incentive plan stock options	0	4
Purchases of treasury stock	(30)	(31)
Excess tax benefits related to stock-based compensation	1	2
Net cash provided by (used in) financing activities	(29)	24
Net decrease in cash and cash equivalents	(642)	(136)
Cash and cash equivalents, beginning of period	1,025	393
Cash and cash equivalents, end of period	$ 383	$ 257