Employee Benefit Plans (Tables)

9 Months Ended

Sep. 30, 2013

Compensation and Retirement Disclosure [Abstract]

Schedule of Net Benefit Costs [Table Text Block]

Net periodic benefit cost is as follows:

	Pension Benefits
	Three months ended   September 30,						Nine months ended    September 30,
	2013			2012			2013			2012
	(Millions)
Components of net periodic benefit cost:
Service cost	$	11		$	10		$	33		$	29
Interest cost	12			14			38			42
Expected return on plan assets	(15		)	(16		)	(45		)	(48		)
Amortization of prior service cost	1			—			1			—
Amortization of net actuarial loss	15			13			45			40
Net actuarial loss from settlements	—			2			—			4
Net periodic benefit cost	$	24		$	23		$	72		$	67

	Other Postretirement Benefits
	Three months ended   September 30,						Nine months ended    September 30,
	2013			2012			2013			2012
	(Millions)
Components of net periodic benefit cost:
Service cost	$	1		$	1		$	2		$	2
Interest cost	2			4			8			10
Expected return on plan assets	(3		)	(3		)	(7		)	(7		)
Amortization of prior service credit	(3		)	(2		)	(7		)	(5		)
Amortization of net actuarial loss	1			2			4			6
Amortization of regulatory liability	1			—			1			—
Net periodic benefit cost	$	(1	)	$	2		$	1		$	6

Schedule of Regulatory Assets [Table Text Block]

Amounts recognized in net regulatory liabilities include:

	Three months ended   September 30,						Nine months ended    September 30,
	2013			2012			2013			2012
	(Millions)
Amortization of prior service credit	$	(1	)	$	(2	)	$	(4	)	$	(4	)
Amortization of net actuarial loss	—			1			2			4