Benefits - Components of Net Periodic Benefit Cost (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014		Mar. 31, 2013
Pension Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure
Service cost	$ 0		$ 1
Interest cost	0		2
Expected return on plan assets	0		(3)
Actuarial loss amortization	0		1
Net periodic benefit cost subtotal	0		1
Regulatory Adjustment	0	[1]	2	[1]
Net periodic benefit cost	0		3
Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure
Service cost	0		0
Interest cost	0		1
Expected return on plan assets	(1)		(2)
Actuarial loss amortization	0		0
Net periodic benefit cost subtotal	(1)		(1)
Regulatory Adjustment	0	[1]	0	[1]
Net periodic benefit cost	$ (1)		$ (1)

[1] The Company has historically recovered certain qualified pension benefit plan and other postretirement benefit plan costs through rates charged to utility customers. Certain utility commissions require that the recovery of these costs be based on the Employee Retirement Income Security Act of 1974, as amended, or other utility commission specific guidelines. The difference between these regulatory-based amounts and the periodic benefit cost calculated pursuant to GAAP is deferred as a regulatory asset or liability and amortized to expense over periods in which this difference will be recovered in rates, as promulgated by the applicable utility commission.