CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
OPERATING ACTIVITIES
Net income (loss)	$ 183.0	$ (67.9)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Depreciation, depletion and amortization	291.6	251.3
Deferred income taxes (benefit)	141.4	(87.7)
Impairment	0.0	5.0
Non-cash share-based compensation	6.4	11.2
Amortization of debt issuance costs and discounts	2.6	2.7
Net (gain) loss from asset sales, inclusive of restructuring costs	(3.7)	(4.6)
Gain from early extinguishment of debt	(25.6)	0.0
Unrealized (gains) losses on marketable securities	0.0	(2.7)
Unrealized (gains) losses on derivative contracts	(188.2)	121.3
Changes in operating assets and liabilities	(183.1)	(32.9)
Net Cash Provided by (Used in) Operating Activities	224.4	195.7
INVESTING ACTIVITIES
Property acquisitions	(4.1)	(1.8)
Expenditures for property, plant and equipment, including exploratory well expense	(245.8)	(316.8)
Proceeds from disposition of assets	12.9	666.7
Net Cash Provided by (Used in) Investing Activities	(237.0)	348.1
FINANCING ACTIVITIES
Checks outstanding in excess of cash balances	(15.9)	(9.3)
Long-term debt issuance costs paid	(0.5)	0.0
Repurchases of senior notes	(127.7)	0.0
Proceeds from credit facility	0.0	56.0
Repayments of credit facility	0.0	(486.0)
Treasury stock repurchases	(0.7)	(6.3)
Dividends paid	(4.8)	0.0
Net Cash Provided by (Used in) Financing Activities	(149.6)	(445.6)
Change in cash, cash equivalents and restricted cash(1)	(162.2)	98.2
Beginning cash, cash equivalents and restricted cash(1)	196.4	28.1
Ending cash, cash equivalents and restricted cash(1)	34.2	126.3
Supplemental Disclosures:
Cash paid for interest, net of capitalized interest	62.1	63.3
Cash paid (refunds received) for income taxes, net	(1.2)	1.5
Cash paid for amounts included in the measurement of lease liabilities	12.2	13.1
Right-of-use assets obtained in exchange for operating lease liabilities	5.3	9.8
Non-cash Investing Activities:
Capital expenditure accruals as of June 30, 2020 and 2019	$ 32.7	$ 74.9