Income Taxes Effective Tax Rate Differences from Statutory Tax Rates (Details)	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Effective Tax Rate Reconciliation [Line Items]
Effective Income Tax Rate Reconciliation, Federal Statutory Rate	35.00%		35.00%		35.00%
Effective Income Tax Rate Reconciliation, Amortization of excess deferred and investment tax credits	(0.30%)		(0.30%)		(0.40%)
Effective Income Tax Rate Reconciliation, Allowance For Other Funds Used During Construction, Equity	0.00%		(0.10%)		(0.60%)
Effective Income Tax Rate Reconciliation, Flow Through Accounting	(2.50%)	[1]	(3.50%)	[1]	(3.40%)	[1]
Effective Income Tax Rate Reconciliation, Prior Year Deferred Adjustment	0.00%		3.60%	[2]	0.00%
Effective Income Tax Rate Reconciliation, Tax Credit	(0.80%)		0.00%		0.00%
Effective Income Tax Rate Reconciliation, Other Adjustments	(0.60%)		(0.10%)		0.10%
Effective Income Tax Rate	30.80%		34.60%		30.70%

[1] The flow-through adjustments relate primarily to an accounting method change for tax purposes that allows us to take a current tax deduction for repair costs that continue to be capitalized for book purposes. We recorded a deferred income tax liability in recognition of the temporary difference created between book and tax treatment and we flowed the tax benefit through to our customers in the form of lower rates as a result of a rate case settlement that occurred during 2010. A regulatory asset was established to reflect the recovery of future increases in taxes payable from customers as the temporary differences reverse. As a result of this regulatory treatment, we continue to record a tax benefit consistent with the flow through method.

[2] The adjustment was a non-recurring unfavorable true-up attributable to property related deferred income taxes. The removal of the impact of such an adjustment is more appropriately reflective of the effective rate on a recurring basis.