Derivative Financial Instruments and Risk Management (Details 4) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Derivative
Balance at beginning of year, net of tax	$ (5)	$ (8)	$ (6)
Gains (losses) deferred during the year, net of tax	(4)	(1)	1
(Gains) losses reclassified to earnings, net of tax	4	4	(3)
Balance at end of year, net of tax	(5)	(5)	(8)
Beginning balance, tax	3	4	3
Gains (losses) deferred, tax	2	1	0
(Gains) losses reclassified to earnings, tax	2	2	(1)
Ending balance, tax	$ 3	$ 3	$ 4