CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Current Assets
Cash and cash equivalents	$ 338.4	$ 443.8
Accounts receivable, net	136.2	155.7
Income tax receivable	18.6	18.6
Hydrocarbon inventories, at lower of average cost or market	6.5	10.4
Prepaid expenses and other	12.9	11.6
Total Current Assets	512.6	640.1
Property, Plant and Equipment (successful efforts method for gas and oil properties)
Proved properties	14,492.6	14,232.5
Unproved properties	881.8	871.5
Gathering and other	307.1	301.8
Material and supplies	33.1	32.7
Total Property, Plant and Equipment	15,714.6	15,438.5
Less Accumulated Depreciation, Depletion and Amortization
Exploration and production	8,980.4	8,797.7
Gathering and other	106.6	101.8
Total Accumulated Depreciation, Depletion and Amortization	9,087.0	8,899.5
Net Property, Plant and Equipment	6,627.6	6,539.0
Fair value of derivative contracts	21.1	0.0
Other noncurrent assets	73.7	66.3
TOTAL ASSETS	7,235.0	7,245.4
Current Liabilities
Checks outstanding in excess of cash balances	9.2	12.3
Accounts payable and accrued expenses	296.2	269.7
Production and property taxes	30.7	30.1
Interest payable	32.8	32.9
Fair value of derivative contracts	45.3	169.8
Total Current Liabilities	414.2	514.8
Long-term debt	2,022.4	2,020.9
Deferred income taxes	872.7	825.9
Asset retirement obligations	227.9	225.8
Fair value of derivative contracts	0.3	32.0
Other long-term liabilities	114.5	123.3
Commitments and contingencies (Note 9)
EQUITY
Common stock – par value $0.01 per share; 500.0 million shares authorized; 242.2 million and 240.7 million shares issued, respectively	2.4	2.4
Treasury stock – 1.7 million and 1.1 million shares, respectively	(29.9)	(22.9)
Additional paid-in capital	1,375.1	1,366.6
Retained earnings	2,250.2	2,173.3
Accumulated other comprehensive income (loss)	(14.8)	(16.7)
Total Shareholders' Equity	3,583.0	3,502.7
TOTAL LIABILITIES AND EQUITY	$ 7,235.0	$ 7,245.4

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.