CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Cash Flows From Operating Activities:
Net income	$ 594	$ 208
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion and amortization	112	143
Amortization of debt issuance costs	1	2
Deferred income taxes	(426)	0
(Gain) loss on derivatives, unsettled	22	(2)
Stock-based compensation	2	4
Other	1	3
Change in assets and liabilities:
Accounts receivable	189	46
Accounts payable	(48)	(17)
Taxes payable	4	(12)
Interest payable	2	(4)
Other assets and liabilities	(11)	(7)
Net cash provided by operating activities	442	364
Cash Flows From Investing Activities:
Capital investments	(258)	(302)
Proceeds from sale of property and equipment	0	6
Other	0	2
Net cash used in investing activities	(258)	(294)
Cash Flows From Financing Activities:
Change in bank drafts outstanding	3	0
Purchase of treasury stock	(21)	0
Preferred stock dividend	0	(27)
Cash paid for tax withholding	(1)	(1)
Net cash used in financing activities	(19)	(28)
Increase in cash and cash equivalents	165	42
Cash and cash equivalents at beginning of year	201	916
Cash and cash equivalents at end of period	$ 366	$ 958