Share-Based Compensation (RSU Compensation Expense) (Details) (RSUs, USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pre-tax compensation expense	$ 12	$ 11	$ 11
Tax benefit	(3)	(3)	(3)
Total expense, net of tax	9	8	8
Total value of RSUs converted	10	9	5
Total fair value of RSUs vested	$ 12	$ 12	$ 10