Cash Flow Disclosures (Tables)

6 Months Ended

Jun. 30, 2015

Nature of Business and Interim Financial Statements [Abstract]

Cash Flow Activities

	Six Months Ended June 30,
(Thousands of dollars)	2015		2014
Net (increase) decrease in operating working capital other than    cash and cash equivalents:
Decrease (increase) in accounts receivable	$	284,542	(53,133)
Decrease (increase) in inventories		(25,547)	5,574
Increase in prepaid expenses		(40,191)	(41,191)
Decrease in deferred income tax assets		5,092	1,895
Increase (decrease) in accounts payable and accrued liabilities		(84,781)	55,729
Increase (decrease) in current income tax liabilities		(31,944)	79,575
Total	$	107,171	48,449
Supplementary disclosures (including discontinued operations):
Cash income taxes paid, net of refunds	$	90,419	234,071
Interest paid, net of amounts capitalized		55,658	41,922
Non-cash investing activities, related to continuing operations:
Asset retirement costs capitalized	$	6,703	12,985
Decrease in capital expenditure accrual		336,952	96,479