CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash Flows From Operating Activities:
Net income (loss)	$ 712.0	$ (2,433.0)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation, depletion and amortization	364.0	349.0
Impairment of natural gas and oil properties		2,321.0
Amortization of debt issuance costs	7.0	12.0
Deferred income taxes	(4.0)	(20.0)
(Gain) loss on derivatives, unsettled	(350.0)	48.0
Stock-based compensation	19.0	24.0
Restructuring charges		30.0
Loss on early extinguishment of debt	70.0	51.0
Other	(2.0)	5.0
Change in assets and liabilities:
Accounts receivable	3.0	53.0
Accounts payable	16.0	(72.0)
Taxes payable	(3.0)	(17.0)
Interest payable	(28.0)	(14.0)
Other assets and liabilities	(15.0)
Net cash provided by operating activities	789.0	337.0
Cash Flows From Investing Activities:
Capital investments	(943.0)	(391.0)
Proceeds from sale of property and equipment	17.0	434.0
Other	5.0
Net cash provided by (used in) investing activities	(921.0)	43.0
Cash Flows From Financing Activities:
Payments on short-term debt	(287.0)	(1.0)
Payments on long-term debt	(1,139.0)	(1,175.0)
Payments on revolving credit facility		(3,268.0)
Borrowings under revolving credit facility		3,152.0
Payments on commercial paper		(242.0)
Borrowings under commercial paper		242.0
Change in bank drafts outstanding		(19.0)
Proceeds from issuance of long-term debt	1,150.0	1,191.0
Debt issuance costs	(18.0)	(17.0)
Proceeds from issuance of common stock		1,247.0
Preferred stock dividend	(8.0)	(27.0)
Other		(4.0)
Net cash provided by (used in) financing activities	(302.0)	1,079.0
Increase (decrease) in cash and cash equivalents	(434.0)	1,459.0
Cash and cash equivalents at beginning of year	1,423.0	15.0
Cash and cash equivalents at end of period	$ 989.0	$ 1,474.0