Balance Sheet Components (Details) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013	Dec. 31, 2012
Valuation and Qualifying Accounts Disclosure [Line Items]
Allowance for Doubtful Accounts Receivable, Current	$ 7,000,000	$ 6,000,000	$ 6,000,000	$ 5,000,000
Finite-Lived Intangible Assets, Accumulated Amortization	176,000,000		170,000,000
Amortization of Intangible Assets	6,000,000	5,000,000
Line of Credit Facility scheduled to terminate in 2017	400,000,000
Credit Facilities - $300 million revolver	300,000,000
Debt Instrument, Covenant Description	.65
Ratio of Indebtedness to Net Capital	0.508
Authorized Short-Term Debt	900,000,000
Short-term Debt	0
Commercial Paper	0
Borrowings	15,000,000
Line of Credit Facility, Remaining Borrowing Capacity	685,000,000
Line of Credit Facility, Current Borrowing Capacity	30,000,000
Pledged Financial Instruments, Not Separately Reported, Securities for Letter of Credit Facilities	45,000,000
letter of credit facility amount available	$ 15,000,000