CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands		Dec. 31, 2016	Dec. 31, 2015	[1]
Current assets
Cash and equivalents		$ 872,797	$ 283,183
Canadian government securities with maturities greater than 90 days at the date of acquisition		111,542	173,288
Accounts receivable, less allowance for doubtful accounts of $1,605 in 2016 and 2015		357,099	522,672
Inventories, at lower of cost or market		127,071	166,788
Prepaid expenses		63,604	212,962
Assets held for sale		27,070	38,340
Total current assets		1,559,183	1,397,233
Property, plant and equipment, at cost less accumulated depreciation, depletion and amortization of $12,607,815 in 2016 and $11,924,193 in 2015		8,316,188	9,818,365
Deferred charges and other assets		420,489	278,214
Total assets		10,295,860	11,493,812
Current liabilities
Current maturities of long-term debt		569,817	18,881
Accounts payable		784,975	1,529,848
Income taxes payable		13,920	4,819
Other taxes payable		28,167	38,498
Other accrued liabilities		102,777	75,286
Liabilities associated with assets held for sale		2,776	7,297
Total current liabilities		1,502,432	1,674,629
Long-term debt, including capital lease obligation		2,422,750	3,040,594
Deferred income taxes		69,081	239,811
Asset retirement obligations		681,528	793,474
Deferred credits and other liabilities		617,490	438,576
Liabilities associated with assets held for sale	[2]	85,900
Stockholders' equity
Cumulative Preferred Stock, par $100, authorized 400,000 shares, none issued
Common Stock, par $1.00, authorized 450,000,000 shares, issued 195,055,724 shares in 2016 and 2015		195,056	195,056
Capital in excess of par value		916,799	910,074
Retained earnings		5,729,596	6,212,201
Accumulated other comprehensive loss	[3]	(628,212)	(704,542)
Treasury stock		(1,296,560)	(1,306,061)
Total stockholders' equity		4,916,679	5,306,728
Total liabilities and stockholders' equity		$ 10,295,860	$ 11,493,812

[1] Reclassified to conform to current presentation. See Note B for additional information.

[2] Liabilities held for sale related to Seal properties in Canada which were sold in January 2017.

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