CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018		Jun. 30, 2017
Cash Flows From Operating Activities:
Net income	$ 259	[1]	$ 635
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion and amortization	285		229
Amortization of debt issuance costs	4		4
(Gain) loss on derivatives, unsettled	54		(319)
Stock-based compensation	9		12
Loss on early extinguishment of debt	8		11
Other	1		(4)
Change in assets and liabilities:
Accounts receivable	12		12
Accounts payable	53		2
Taxes payable	(4)		5
Interest payable	(1)		(4)
Inventories	(7)		(2)
Other assets and liabilities	(9)		(3)
Net cash provided by operating activities	664		578
Cash Flows From Investing Activities:
Capital investments	(684)		(619)
Proceeds from sale of property and equipment	6		12
Other	3		1
Net cash used in investing activities	(675)		(606)
Cash Flows From Financing Activities:
Payments on long-term debt	(1,191)		(287)
Payments on revolving credit facility	(645)
Borrowings under revolving credit facility	1,005
Change in bank drafts outstanding			3
Debt issuance costs	(9)
Preferred stock dividend	(27)
Cash paid for tax withholding	(1)
Net cash used in financing activities	(868)		(284)
Decrease in cash and cash equivalents	(879)		(312)
Cash and cash equivalents at beginning of year	916		1,423
Cash and cash equivalents at end of period	$ 37		$ 1,111

[1] In 2018, deferred tax activity incurred in other comprehensive income was offset by a valuation allowance.