CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Current Assets
Cash and cash equivalents	$ 3.4	$ 166.3
Accounts receivable, net	97.9	108.4
Income tax receivable	165.0	37.4
Fair value of derivative contracts	169.4	1.5
Prepaid expenses and other current assets	10.7	11.6
Total Current Assets	446.4	325.2
Property, Plant and Equipment (successful efforts method for oil and gas properties)
Proved properties	9,786.2	9,574.9
Unproved properties	543.6	599.1
Gathering and other	165.5	164.2
Materials and supplies	16.5	15.6
Total Property, Plant and Equipment	10,511.8	10,353.8
Less Accumulated Depreciation, Depletion and Amortization
Exploration and production	5,482.4	5,250.5
Gathering and other	66.3	61.0
Total Accumulated Depreciation, Depletion and Amortization	5,548.7	5,311.5
Net Property, Plant and Equipment	4,963.1	5,042.3
Fair value of derivative contracts	6.2	0.2
Operating lease right-of-use assets, net	54.1	56.8
Other noncurrent assets	54.3	53.3
TOTAL ASSETS	5,524.1	5,477.8
Current Liabilities
Checks outstanding in excess of cash balances	2.3	18.3
Accounts payable and accrued expenses	157.0	227.2
Production and property taxes	9.2	18.9
Current portion of long term debt	274.9	0.0
Interest payable	27.9	31.0
Fair value of derivative contracts	1.8	18.7
Current operating lease lease liabilities	20.3	18.0
Asset retirement obligations	6.2	6.0
Total Current Liabilities	499.6	338.1
Long-term debt	1,589.4	2,015.6
Deferred income taxes	416.1	274.5
Asset retirement obligations	94.9	94.9
Fair value of derivative contracts	3.2	0.5
Operating lease liabilities	39.2	44.8
Other long-term liabilities	36.8	48.8
Commitments and contingencies (Note 11)
EQUITY
Common stock – par value $0.01 per share; 500.0 million shares authorized; 247.2 million and 242.1 million shares issued, respectively	2.5	2.4
Treasury stock – 4.9 million and 4.4 million shares, respectively	(56.6)	(55.4)
Additional paid-in capital	1,463.3	1,456.5
Retained earnings	1,447.8	1,269.6
Accumulated other comprehensive income (loss)	(12.1)	(12.5)
Total Common Shareholders' Equity	2,844.9	2,660.6
TOTAL LIABILITIES AND EQUITY	$ 5,524.1	$ 5,477.8