Schedule II - Valuation and Qualifying Accounts (Details) - Allowance for Trade Receivables [Member] - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period		$ 3	$ 3	$ 2
Additions Charged to Income		0	3	2
Deductions From Reserves	[1]	2	3	1
Balance at End of Period		$ 1	$ 3	$ 3

[1] Deductions from reserves represent losses or expenses for which the respective reserves were created. In the case of the uncollectible accounts reserve, such deductions are net of recoveries of amounts previously written off.