Additional disclosures regarding cash flow activities are provided below.


	Three Months Ended March 31,
(Thousands of dollars)	2012			2011
Net (increase) decrease in operating working capital other than cash and cash equivalents:
(Increase) decrease in accounts receivable	$	69,126			(391,217	)
(Increase) decrease in inventories		4,962			12,032
(Increase) decrease in prepaid expenses		(51,508	)		(2,146	)
(Increase) decrease in deferred income tax assets		5,522			4,586
Increase (decrease) in accounts payable and accrued liabilities		227,067			236,926
Increase (decrease) in current income tax liabilities		43,165			(603	)

Total	$	298,334			(140,422	)

Supplementary disclosures:
Cash income taxes paid	$	160,210			147,547
Interest paid more (less) than amounts capitalized		490			(4,921	)