Shareholders' Equity - Schedule of Share Repurchases (Details) (USD $) In Millions, except Share data, unless otherwise specified	9 Months Ended		3 Months Ended							9 Months Ended	12 Months Ended	1 Months Ended	10 Months Ended	22 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014 Common Stock	Jun. 30, 2014 Common Stock	Mar. 31, 2014 Common Stock	Dec. 31, 2013 Common Stock	Sep. 30, 2013 Common Stock	Jun. 30, 2013 Common Stock	Mar. 31, 2013 Common Stock	Sep. 30, 2014 Common Stock	Dec. 31, 2013 Common Stock	Nov. 06, 2014 Common Stock Subsequent event	Nov. 06, 2014 Common Stock Subsequent event	Nov. 06, 2014 Common Stock Subsequent event
Equity, Class of Treasury Stock [Line Items]
Number of Shares Repurchased			9,623,309	7,051,842	1,350,443	291,138	732,092	9,574,963	1,914,566	18,025,594	12,512,759	2,766,854	20,792,448	33,305,207
Total Payments(in millions)	$ 438	$ 259	$ 226	$ 177	$ 35	$ 6	$ 14	$ 205	$ 39	$ 438	$ 264	$ 61	$ 499	$ 763
Average Price Paid Per Share			$ 23.47	$ 25.14	$ 25.92	$ 19.74	$ 19.47	$ 21.42	$ 20.46	$ 24.30	$ 21.12	$ 22.08	$ 24.01	$ 22.92