CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands		Sep. 30, 2015	Dec. 31, 2014
Current assets
Cash and cash equivalents		$ 878,667	$ 1,193,308	[1]
Canadian government securities with maturities greater than 90 days at the date of acquisition		415,097	461,313	[1]
Accounts receivable, less allowance for doubtful accounts of $1,605 in 2015 and $1,609 in 2014		432,791	873,277	[1]
Inventories, at lower of cost or market
Crude oil		53,170	51,757	[1]
Materials and supplies		127,426	190,976	[1]
Prepaid expenses		157,455	77,281	[1]
Deferred income taxes		48,781	55,107	[1]
Assets held for sale		52,416	376,130	[1]
Total current assets		2,165,803	3,279,149	[1]
Property, plant and equipment, at cost less accumulated depreciation, depletion and amortization of $11,617,367 in 2015 and $9,503,524 in 2014		10,168,750	13,331,047	[1]
Deferred charges and other assets		293,409	62,582	[1]
Assets held for sale	[1]		50,960
Total assets		12,627,962	16,723,738	[1]
Current liabilities
Current maturities of long-term debt		12,173	465,388	[1]
Accounts payable and accrued liabilities		1,621,415	2,471,897	[1]
Income taxes payable		7,588	59,054	[1]
Liabilities associated with assets held for sale		10,059	151,548	[1]
Total current liabilities		1,651,235	3,147,887	[1]
Long-term debt, including capital lease obligation		3,327,689	2,517,669	[1]
Deferred income taxes		306,379	1,193,864	[1]
Asset retirement obligations		885,984	841,526	[1]
Deferred credits and other liabilities		$ 428,221	441,048	[1]
Liabilities associated with assets held for sale	[1]		$ 8,310
Stockholders' equity
Cumulative Preferred Stock, par $100, authorized 400,000 shares, none issued				[1]
Common Stock, par $1.00, authorized 450,000,000 shares, issued 195,055,724 shares in 2015 and 195,040,149 shares in 2014		$ 195,056	$ 195,040	[1]
Capital in excess of par value		902,241	906,741	[1]
Retained earnings		6,859,542	8,728,032	[1]
Accumulated other comprehensive loss	[2]	(621,759)	(170,255)	[1]
Treasury stock, 23,030,991 shares of Common Stock in 2015 and 17,540,636 shares of Common Stock in 2014, at cost		(1,306,626)	(1,086,124)	[1]
Total stockholders' equity		6,028,454	8,573,434	[1]
Total liabilities and stockholders' equity		$ 12,627,962	$ 16,723,738	[1]

[1] Reclassified to conform to current presentation.

[2] All amounts are presented net of income taxes.