Basis of Presentation (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013 sqmi	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Basis of Presentation [Abstract]
revenue overstatment	$ 9	$ 3	$ 3	$ 2	$ 1
Incorporated Cities	52
Service Area Sq Miles	4,000
Number of Retail Customers	836,070
Service area population	1,700,000
Percent of State's Population	44.00%
Entity Number of Employees	2,596
Number of Union Employees	795
Number of Union Employees Subject to Agreement A	760
Number of Union Employees Subject to Agreement B	35