Employee Benefit Plans (Tables)

6 Months Ended

Jun. 30, 2011

Employee Benefit Plans [Abstract]

Net periodic benefit expense

	Pension Benefits
	Three months						Six months
	ended June 30,						ended June 30,
	2011			2010			2011			2010
	(Millions)
Components of net periodic benefit expense:
Service cost	$	10		$	10		$	20		$	18
Interest cost		15			16			32			32
Expected return on plan assets		(19	)		(17	)		(38	)		(35	)
Amortization of net actuarial loss		10			8			19			17
Net periodic benefit expense (income)	$	16		$	17		$	33		$	32

	Other Postretirement Benefits
	Three months						Six months
	ended June 30,						ended June 30,
	2011			2010			2011			2010
	(Millions)
Components of net periodic benefit expense:
Service cost	$	—		$	—		$	1		$	1
Interest cost		3			4			7			8
Expected return on plan assets		(2	)		(2	)		(5	)		(5	)
Amortization of prior service cost (credit)		(2	)		(4	)		(5	)		(7	)
Amortization of net actuarial loss		1			1			2			1
Amortization of regulatory asset		—			1			—			1
Net periodic benefit expense (income)	$	—		$	—		$	—		$	(1	)