Cash Flow Disclosures (Tables)

3 Months Ended

Mar. 31, 2013

Supplemental Cash Flow Elements [Abstract]

Cash Flow Activities

Additional disclosures regarding cash flow activities are provided below.

	Three Months Ended March 31,
(Thousands of dollars)	2013			2012
Net (increase) decrease in operating working capital other than cash and cash equivalents:
Decrease in accounts receivable	$	182,714			69,126
Decrease in inventories		126,826			4,962
Increase in prepaid expenses		(54,119	)		(51,508	)
Decrease in deferred income tax assets		24,082			5,522
Increase (decrease) in accounts payable and accrued liabilities		(191,616	)		229,804
Increase in current income tax liabilities		123,575			43,165
Total	$	211,462			301,071
Supplementary disclosures:
Cash income taxes paid	$	47,877			160,210
Interest paid more (less) than amounts capitalized		(10,519	)		490