CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash Flows From Operating Activities:
Net income	$ 230	$ 712
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion and amortization	436	364
Amortization of debt issuance costs	6	7
Impairments	161
Deferred income taxes		(4)
(Gain) loss on derivatives, unsettled	113	(350)
Stock-based compensation	12	19
Loss on early extinguishment of debt	8	70
Other	7	(2)
Change in assets and liabilities:
Accounts receivable	(7)	3
Accounts payable	60	16
Taxes payable		(3)
Interest payable	(5)	(28)
Inventories	(9)	(1)
Other assets and liabilities	(41)	(14)
Net cash provided by operating activities	971	789
Cash Flows From Investing Activities:
Capital investments	(1,008)	(943)
Proceeds from sale of property and equipment	9	17
Other	4	5
Net cash used in investing activities	(995)	(921)
Cash Flows From Financing Activities:
Payments on short-term debt		(287)
Payments on long-term debt	(1,191)	(1,139)
Payments on revolving credit facility	(1,122)
Borrowings under revolving credit facility	1,482
Change in bank drafts outstanding	10
Proceeds from issuance of long-term debt		1,150
Debt issuance costs	(9)	(18)
Purchase of treasury stock	(25)
Preferred stock dividend	(27)	(8)
Cash paid for tax withholding	(1)
Net cash used in financing activities	(883)	(302)
Decrease in cash and cash equivalents	(907)	(434)
Cash and cash equivalents at beginning of year	916	1,423
Cash and cash equivalents at end of period	$ 9	$ 989