Property, Plant and Equipment (Tables)

12 Months Ended

Dec. 31, 2016

Property, Plant And Equipment [Abstract]

Schedule of Property, Plant and Equipment

	December 31, 2016				December 31, 2015
(Thousands of dollars)	Cost		Net		Cost	Net
Exploration and production1	$	20,767,772	8,214,740	2	21,607,962	9,723,222	2
Corporate and other		156,231	101,448		134,596	95,143
	$	20,924,003	8,316,188		21,742,558	9,818,365
1  Includes mineral rights as follows:	$	595,138	188,689		1,075,040	612,518

2.  Includes $48,053 in 2016 and $50,924 in 2015

  related to administrative assets and support equipment.

Schedule of Recognized Impairments

	December 31,
(Thousands of dollars)		2016	2015	2014
Gulf of Mexico	$	–	328,982	14,267
Canada		95,088	683,574	37,047	*
Malaysia		–	1,480,600	–
	$	95,088	2,493,156	51,314

*  This amount represented the writeoff of goodwill associated with an oil and gas company acquired in 2000.

Net Changes in Capitalized Exploratory Well Costs

(Thousands of dollars)	2016		2015	2014
Beginning balance at January 1	$	130,514	120,455	393,030
Additions to capitalized exploratory well costs pending the      determination of proved reserves		17,986	64,578	2,874
Reclassifications to proved properties based on the      determination of proved reserves		–	–	(91,236)
Reduction of capitalized exploratory well costs due to      partial asset sale in Malaysia		–	–	(122,175)
Capitalized exploratory well costs charged to expense		–	(54,519)	(62,038)
Ending balance at December 31	$	148,500	130,514	120,455

Aging of Capitalized Exploratory Well Costs

	2016				2015				2014
(Thousands of dollars)	Amount		No. of Wells	No. of Projects	Amount		No. of Wells	No. of Projects	Amount		No. of Wells	No. of Projects
Aging of capitalized well   costs:
Zero to one year	$	20,481	1	1	$	66,032	7	6	$	–	–	–
One to two years		63,527	5	5		–	–	–		59,330	3	1
Two to three years		–	–	–		57,876	3	–		6,606	3	–
Three years or more		64,492	6	–		6,606	3	–		54,519	2	2
	$	148,500	12	6	$	130,514	13	6	$	120,455	8	3