Employee Benefit Plans (Tables)

9 Months Ended

Sep. 30, 2011

Employee Benefit Plans [Abstract]

Components of Net Periodic Benefit Cost

							Other Postretirement
	Pension Benefits						Benefits
	Three Months Ended						Three Months Ended
	September 30,						September 30,
	2011			2010			2011		2010
	-Millions of Dollars-
Components of Net Periodic Benefit Cost
Service Cost	$	2		$	2		$	1	$	—
Interest Cost		4			4			1		1
Expected Return on Plan Assets		(4	)		(3	)		—		—
Amortization of Net Loss		2			1			—		—
Net Periodic Benefit Cost	$	4		$	4		$	2	$	1

							Other Postretirement
	Pension Benefits						Benefits
	Nine Months Ended						Nine Months Ended
	September 30,						September 30,
	2011			2010			2011			2010
	-Millions of Dollars-
Components of Net Periodic Benefit Cost
Service Cost	$	7		$	6		$	2		$	2
Interest Cost		12			11			3			3
Expected Return on Plan Assets		(12	)		(10	)		—			—
Amortization of Prior Service Costs		—			—			(1	)		(1	)
Amortization of Net Loss		5			4			—			—
Net Periodic Benefit Cost	$	12		$	11		$	4		$	4