CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Current Assets
Cash and cash equivalents	$ 89.9	$ 0.0
Accounts receivable, net	80.2	104.3
Income tax receivable	68.8	75.9
Fair value of derivative contracts	0.0	87.5
Prepaid expenses	7.3	12.7
Other current assets	0.2	0.2
Total Current Assets	246.4	280.6
Property, Plant and Equipment (successful efforts method for oil and gas properties)
Proved properties	9,250.1	9,096.9
Unproved properties	706.5	705.5
Gathering and other	171.3	167.7
Materials and supplies	29.8	29.9
Total Property, Plant and Equipment	10,157.7	10,000.0
Less Accumulated Depreciation, Depletion and Amortization
Exploration and production	4,994.3	4,882.4
Gathering and other	61.0	58.1
Total Accumulated Depreciation, Depletion and Amortization	5,055.3	4,940.5
Net Property, Plant and Equipment	5,102.4	5,059.5
Fair value of derivative contracts	6.7	35.4
Operating Lease, Right-of-Use Asset	61.4	0.0
Other noncurrent assets	53.3	49.6
Noncurrent assets held for sale	0.0	692.7
TOTAL ASSETS	5,470.2	6,117.8
Current Liabilities
Checks outstanding in excess of cash balances	10.3	14.6
Accounts payable and accrued expenses	216.0	258.1
Production and property taxes	22.0	24.1
Long-term Debt, Current Maturities	51.7	0.0
Interest payable	33.0	32.4
Fair value of derivative contracts	60.3	0.0
Operating Lease, Liability, Current	20.1	0.0
Asset retirement obligations	5.9	5.1
Total Current Liabilities	419.3	334.3
Long-term debt	2,026.7	2,507.1
Deferred income taxes	151.2	269.2
Asset retirement obligations	96.2	96.9
Fair value of derivative contracts	1.5	0.7
Operating Lease, Liability, Noncurrent	49.4	0.0
Other long-term liabilities	89.8	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; 242.0 million and 239.8 million shares issued, respectively	2.4	2.4
Treasury stock – 3.9 million and 3.1 million shares, respectively	(51.8)	(45.6)
Additional paid-in capital	1,440.2	1,431.9
Retained earnings	1,259.8	1,376.5
Accumulated other comprehensive income (loss)	(14.5)	(14.3)
Total Common Shareholders' Equity	2,636.1	2,750.9
TOTAL LIABILITIES AND EQUITY	$ 5,470.2	$ 6,117.8

Sum of the carrying values as of the balance sheet date of obligations incurred through that date and due within one year (or the operating cycle, if longer), including liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received, taxes, interest, rent and utilities, accrued salaries and bonuses, payroll taxes and fringe benefits.

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- Definition

Amount due from customers or clients, within one year of the balance sheet date (or the normal operating cycle, whichever is longer), for goods or services (including trade receivables) that have been delivered or sold in the normal course of business, reduced to the estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection.