Share-Based Compensation Plans Schedule of Performance-based plans (Details) (Performance-based Awards [Member], USD $) In Millions, except Share data in Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Performance-based Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Target PSAs granted	1,135		1,369		1,715
Fair value	$ 58	[1]	$ 47	[1]	$ 50	[1]
Number of shares that would be issued based on current performance levels	1,702		2,451		1,443
Unamortized expense, based on current performance levels	$ 70		$ 40		$ 0

[1] Represents per share weighted average fair value of award at date of grant.