CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Current Assets
Cash and cash equivalents	$ 92.4	$ 0.0
Accounts receivable, net	104.3	104.3
Income tax receivable	75.5	75.9
Fair value of derivative contracts	69.8	87.5
Prepaid expenses	8.1	12.9
Total Current Assets	350.1	280.6
Property, Plant and Equipment (successful efforts method for oil and gas properties)
Proved properties	9,416.9	9,096.9
Unproved properties	698.3	705.5
Gathering and other	162.7	167.7
Materials and supplies	19.3	29.9
Total Property, Plant and Equipment	10,297.2	10,000.0
Less Accumulated Depreciation, Depletion and Amortization
Exploration and production	5,153.3	4,882.4
Gathering and other	58.5	58.1
Total Accumulated Depreciation, Depletion and Amortization	5,211.8	4,940.5
Net Property, Plant and Equipment	5,085.4	5,059.5
Fair value of derivative contracts	23.2	35.4
Operating lease right-of-use assets, net	57.4	0.0
Other noncurrent assets	54.5	49.6
Noncurrent assets held for sale	0.0	692.7
TOTAL ASSETS	5,570.6	6,117.8
Current Liabilities
Checks outstanding in excess of cash balances	0.7	14.6
Accounts payable and accrued expenses	206.2	258.1
Production and property taxes	17.7	24.1
Current portion of long term debt	51.7	0.0
Interest payable	33.0	32.4
Fair value of derivative contracts	0.8	0.0
Current operating lease lease liabilities	18.4	0.0
Asset retirement obligations	6.7	5.1
Total Current Liabilities	335.2	334.3
Long-term debt	2,029.4	2,507.1
Deferred income taxes	208.0	269.2
Asset retirement obligations	95.5	96.9
Fair value of derivative contracts	0.4	0.7
Operating lease liabilities	45.3	0.0
Other long-term liabilities	86.8	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 – 4.3 million and 3.1 million shares, respectively	(54.8)	(45.6)
Additional paid-in capital	1,451.9	1,431.9
Retained earnings	1,384.8	1,376.5
Accumulated other comprehensive income (loss)	(14.3)	(14.3)
Total Common Shareholders' Equity	2,770.0	2,750.9
TOTAL LIABILITIES AND EQUITY	$ 5,570.6	$ 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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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- 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.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130549-203045

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(3))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682