CONSOLIDATED BALANCE SHEET - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets
Cash and cash equivalents	$ 480,047	$ 498,542
Accounts receivable, net	216,004	191,045
Income taxes receivable	56,666	10,298
Inventories	8,006	13,304
Current assets held for sale	1,440	0
Other current assets	2,794	2,692
Total current assets	764,957	715,881
Properties and equipment, net (Successful efforts method)	3,072,204	4,250,125
Equity method investments	86,077	129,524
Assets held for sale	778,855	0
Other assets	25,251	27,039
TOTAL ASSETS	4,727,344	5,122,569
Current liabilities
Accounts payable	238,045	168,411
Current portion of long-term debt	304,000	0
Accrued liabilities	27,441	21,492
Interest payable	27,575	27,650
Derivative instruments	30,637	40,259
Current liabilities held for sale	2,352	0
Total current liabilities	630,050	257,812
Long-term debt, net	1,217,891	1,520,530
Deferred income taxes	227,030	579,447
Asset retirement obligations	43,601	131,733
Liabilities held for sale	15,748	0
Postretirement benefits	29,396	36,259
Other liabilities	39,723	29,121
Total liabilities	2,203,439	2,554,902
Commitments and contingencies
Stockholders' equity
Common stock	47,555	47,504
Additional paid-in capital	1,742,419	1,727,310
Retained earnings	1,162,430	1,098,703
Accumulated other comprehensive income	2,077	985
Treasury stock	(430,576)	(306,835)
Total stockholders' equity	2,523,905	2,567,667
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	$ 4,727,344	$ 5,122,569

Carrying value as of the balance sheet date of liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received that are used in an entity's business. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Carrying value as of the balance sheet date of obligations incurred and payable, pertaining to costs that are statutory in nature, are incurred on contractual obligations, or accumulate over time and for which invoices have not yet been received or will not be rendered. Examples include taxes, interest, rent and utilities. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).