CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Current Assets
Cash and cash equivalents	$ 166.3	$ 0.0
Accounts receivable, net	108.4	104.3
Income tax receivable	37.4	75.9
Fair value of derivative contracts	1.5	87.5
Prepaid expenses	11.4	12.7
Other current assets	0.2	0.2
Total Current Assets	325.2	280.6
Property, Plant and Equipment (successful efforts method for oil and gas properties)
Proved properties	9,574.9	9,096.9
Unproved properties	599.1	705.5
Gathering and other	164.2	167.7
Materials and supplies	15.6	29.9
Total Property, Plant and Equipment	10,353.8	10,000.0
Less Accumulated Depreciation, Depletion and Amortization
Exploration and production	5,250.5	4,882.4
Gathering and other	61.0	58.1
Total Accumulated Depreciation, Depletion and Amortization	5,311.5	4,940.5
Net Property, Plant and Equipment	5,042.3	5,059.5
Fair value of derivative contracts	0.2	35.4
Operating lease right-of-use assets, net	56.8	0.0
Other noncurrent assets	53.3	49.6
Noncurrent assets held for sale	0.0	692.7
TOTAL ASSETS	5,477.8	6,117.8
Current Liabilities
Checks outstanding in excess of cash balances	18.3	14.6
Accounts payable and accrued expenses	227.2	258.1
Production and property taxes	18.9	24.1
Interest payable	31.0	32.4
Fair value of derivative contracts	18.7	0.0
Current operating lease liabilities	18.0	0.0
Asset retirement obligations	6.0	5.1
Total Current Liabilities	338.1	334.3
Long-term debt	2,015.6	2,507.1
Deferred income taxes	274.5	269.2
Asset retirement obligations	94.9	96.9
Fair value of derivative contracts	0.5	0.7
Operating lease liabilities	44.8	0.0
Other long-term liabilities	48.8	97.4
Other long-term liabilities held for sale	0.0	61.3
Commitments and Contingencies (Note 11)
EQUITY
Common stock - par value $0.01 per share; 500.0 million shares authorized; 242.1 million and 239.8 million shares issued, respectively	2.4	2.4
Treasury stock - 4.4 million and 3.1 million shares, respectively	(55.4)	(45.6)
Additional paid-in capital	1,456.5	1,431.9
Retained earnings	1,269.6	1,376.5
Accumulated other comprehensive income (loss)	(12.5)	(14.3)
Total Common Shareholders' Equity	2,660.6	2,750.9
TOTAL LIABILITIES AND EQUITY	$ 5,477.8	$ 6,117.8