Accumulated Other Comprehensive Loss (Tables)

12 Months Ended

Dec. 31, 2011

Accumulated Other Comprehensive Loss [Abstract]

Schedule Of The Components Of Other Comprehensive Loss

	Commodity Derivatives			Treasury Lock			Other			Accumulated Other Comprehensive Loss
	(millions of dollars)
Balance, December 31, 2008	$	(120	)	$	(25	)	$	(10	)	$	(155	)
Current year change		21			3			(7	)		17
Balance, December 31, 2009		(99	)		(22	)		(17	)		(138	)
Current year change		21			11			—			32
Balance, December 31, 2010		(78	)		(11	)		(17	)		(106	)
Current year change		49			1			(7	)		43
Balance, December 31, 2011	$	(29	)	$	(10	)	$	(24	)	$	(63	)

Schedule Of Income Tax Expense (Benefit) Relating To Accumulated Other Comprehensive Income

For the Year Ended:	Commodity Derivatives		Treasury Lock			Other			Accumulated Other Comprehensive Loss
	(millions of dollars)
December 31, 2009	$	15		$	2	$	(5	)	$	12
December 31, 2010	$	14		$	7	$	—		$	21
December 31, 2011	$	32		$	—	$	(4	)	$	28