Common Stock (Details) (USD $) Share data in Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Equity, Class of Treasury Stock [Line Items]
Payments for repurchase of common stock	$ 600,000,000	$ 400,000,000
Common Stock [Member]
Equity, Class of Treasury Stock [Line Items]
Common stock repurchased (in shares)	11.8	10.0
Share repurchases program, authorized amount	2,000,000,000
Stock repurchase program, remaining authorized repurchase amount	$ 1,500,000,000