Share-Based Compensation (Stock Option Compensation Expense) (Details) (Stock Options, USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pre-tax compensation expense	$ 2	$ 2	$ 7
Tax benefit	(1)	(1)	(2)
Total expense, net of tax	1	1	5
Total intrinsic value of options exercised	5	10	8
Total fair value of options vested	2	5	7
Cash received from the exercise of stock options	$ 13	$ 9	$ 4