Pension Plans and Other Postretirement Benefits (Tables)

9 Months Ended

Sep. 30, 2011

Table Text Block [Abstract]

Components of Net Periodic Benefit Cost Table

	Pension Benefits				Other Benefits
	Three Months Ended				Three Months Ended
	September 30,				September 30,
millions	2011		2010		2011		2010
Components of net periodic benefit cost
Service cost	$	20	$	17	$	3	$	3
Interest cost		21		21		4		4
Expected return on plan assets		(21)		(21)		—		—
Amortization of net actuarial loss (gain)		22		14		—		(1)
Amortization of net prior service cost (credit)		—		1		—		—
Net periodic benefit cost	$	42	$	32	$	7	$	6

	Pension Benefits				Other Benefits
	Nine Months Ended				Nine Months Ended
	September 30,				September 30,
millions	2011		2010		2011		2010
Components of net periodic benefit cost
Service cost	$	59	$	52	$	7	$	7
Interest cost		64		63		12		12
Expected return on plan assets		(64)		(62)		—		—
Amortization of net actuarial loss (gain)		64		49		—		(2)
Amortization of net prior service cost (credit)		1		2		—		(1)
Net periodic benefit cost	$	124	$	104	$	19	$	16