Balance Sheet Components Allowance for Uncollectible accounts activity (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance as of beginning of year	$ 5	$ 6	$ 5
Increase in provision	6	6	11
Allowance for Doubtful Accounts Receivable, Charge-offs	(5)	(7)	(10)
Balance as of end of year	$ 6	$ 5	$ 6