Income Taxes (Tables)

12 Months Ended

Dec. 31, 2017

Income Taxes [Abstract]

Components of Income (Loss) from Continuing Operations Before Income Taxes and Income Tax Expense

(Thousands of dollars)	2017		2016	2015
Income (loss) from continuing operations before income taxes
United States	$	(299,349)	(595,196)	(1,259,268)
Foreign		371,151	102,081	(2,022,994)
Total	$	71,802	(493,115)	(3,282,262)
Income tax expense (benefit)
Federal – Current	$	–	–	(9,435)
– Deferred		156,065	(197,450)	(241,127)
Total Federal		156,065	(197,450)	(250,562)
State		4,230	13,984	(5,294)
Foreign – Current		122,318	146,861	(40,550)
– Deferred		100,125	(182,567)	(730,084)
Total Foreign		222,443	(35,706)	(770,634)
Total	$	382,738	(219,172)	(1,026,490)

Effective Income Tax Rates

(Thousands of dollars)	2017		2016	2015
Income tax expense (benefit) based on the U.S. statutory tax rate	$	25,131	(172,590)	(1,148,792)
Revaluation of deferred tax (US tax reform)		118,004	–	–
Deferred tax effect of deemed repatriation of foreign invested earnings (U.S. tax reform)		156,000	–	–
Deferred tax effect on Canadian earnings no longer indefinitely invested		65,000	–	–
Foreign income (loss) subject to foreign tax rates different than      the U.S. statutory rate		12,658	8,582	49,739
State income taxes, net of federal benefit		2,438	9,090	(3,441)
U.S. tax benefit on certain foreign upstream investments		(32,926)	(21,336)	(16,939)
Deferred tax on distribution of foreign earnings		–	–	188,461
Tax effects on sale of Canadian assets		–	(89,473)	–
Tax effects on sale of Malaysian assets		–	2,080	(122,559)
Increase in deferred tax asset valuation allowance related      to other foreign exploration expenditures		18,601	25,734	40,788
Other, net		17,832	18,741	(13,747)
Total	$	382,738	(219,172)	(1,026,490)

Analysis of Deferred Tax Assets and Deferred Tax Liabilities Showing Tax Effects of Significant Temporary Differences

(Thousands of dollars)	2017		2016
Deferred tax assets
Property and leasehold costs	$	488,584	572,481
Liabilities for dismantlements		98,444	170,946
Postretirement and other employee benefits		134,444	214,288
Alternative minimum tax		29,710	29,710
Foreign tax credit carryforwards		228,159	33,295
U. S. net operating loss		272,930	454,231
Other deferred tax assets		13,892	16,541
Total gross deferred tax assets		1,266,163	1,491,492
Less valuation allowance		(476,256)	(305,389)
Net deferred tax assets		789,907	1,186,103
Deferred tax liabilities
Deferred tax on undistributed foreign earnings		(65,000)	–
Accumulated depreciation, depletion and amortization		(669,638)	(867,343)
Other deferred tax liabilities		(2,824)	(21,908)
Total gross deferred tax liabilities		(737,462)	(889,251)
Net deferred tax assets	$	52,445	296,852

Reconciliation of Beginning and Ending Amount of Consolidated Liability for Unrecognized Income Tax Benefits

(Thousands of dollars)	2017		2016	2015
Balance at January 1	$	7,417	6,631	6,011
Additions for tax positions related to current year		769	756	821
Settlements due to lapse of time		(4,834)	–	–
Foreign currency translation effect		85	30	(201)
Balance at December 31	$	3,437	7,417	6,631