Fair Value Measurements (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Investment Income, Nonoperating	$ 10	$ 7	$ 21	$ 18
Asset-backed Securities [Member] | Moody's, A2 Rating [Member]
Percentage Of Company's Investments With Credit Quality Rating Less Than Single A And A2			1.00%
Asset-backed Securities [Member] | Fitch, A Rating [Member]
Percentage Of Company's Investments With Credit Quality Rating Less Than Single A And A2			1.00%