CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014		Dec. 31, 2013
Current assets
Cash and cash equivalents	$ 648,612		$ 750,155
Canadian government securities with maturities greater than 90 days at the date of acquisition	372,003		374,842
Accounts receivable, less allowance for doubtful accounts of $1,609 in 2014 and 2013	1,007,125		999,872
Inventories, at lower of cost or market Crude oil	38,104		40,077
Materials and supplies	255,132		254,118
Prepaid expenses	125,984		83,856
Deferred income taxes	55,146		61,991
Assets held for sale	871,453		943,732
Total current assets	3,373,559		3,508,643
Property, plant and equipment, at cost less accumulated depreciation, depletion and amortization of $8,850,951 in 2014 and $8,540,239 in 2013	13,654,991		13,481,055
Goodwill	38,702		40,259
Deferred charges and other assets	95,269		98,123
Assets held for sale	388,617		381,404
Total assets	17,551,138		17,509,484
Current liabilities
Current maturities of long-term debt	30,647		26,249
Accounts payable and accrued liabilities	2,149,085		2,335,712
Income taxes payable	288,101		222,930
Liabilities associated with assets held for sale	589,011		639,140
Total current liabilities	3,056,844		3,224,031
Long-term debt, including capital lease obligation	3,415,621		2,936,563
Deferred income taxes	1,485,616		1,466,100
Asset retirement obligations	854,270		852,488
Deferred credits and other liabilities	337,957		339,028
Liabilities associated with assets held for sale	96,752		95,544
Stockholders' equity
Cumulative Preferred Stock, par $100, authorized 400,000 shares, none issued	0		0
Common Stock, par $1.00, authorized 450,000,000 shares, issued 194,945,904 shares in 2014 and 194,920,155 shares in 2013	194,946		194,920
Capital in excess of par value	876,647		902,633
Retained earnings	8,157,972		8,058,792
Accumulated other comprehensive income	37,463	[1]	172,119	[1]
Treasury stock, 15,499,120 shares of Common Stock in 2014 and 11,513,642 shares of Common Stock in 2013, at cost	(962,950)		(732,734)
Total stockholders' equity	8,304,078		8,595,730
Total liabilities and stockholders' equity	$ 17,551,138		$ 17,509,484

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