Earnings Per Share, Share Repurchases and Dividends on Common Stock (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended			39 Months Ended	20 Months Ended	1 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Sep. 30, 2013	Dec. 31, 2014	Dec. 31, 2014	Jun. 16, 2010	May 15, 2013	Dec. 04, 2014
Stock Repurchase [Line Items]
Shares repurchased	21.4	27.3	20.9
June 2010 Share Repurchase Program Original Authorization
Stock Repurchase [Line Items]
Amount Authorized							$ 5,350
Total shares retired				83.7
Treasury Stock Acquired, Average Cost Per Share				$ 63.86
Shares repurchased	0	18.6	20.9
May 2013 Share Repurchase Program Original Authorization
Stock Repurchase [Line Items]
Amount Authorized								4,000
Total shares retired					30.1
Treasury Stock Acquired, Average Cost Per Share					$ 118.30
Shares repurchased	21.4	8.7	0
Share Repurchases-Notes to the Table
Amount repurchased	3,600				3,600	3,600
Amount remaining under authorization for share repurchases	447				447	447
December 2014 Share Repurchase Original Authorization
Stock Repurchase [Line Items]
Amount Authorized									$ 3,000
Total shares retired						0
Treasury Stock Acquired, Average Cost Per Share						$ 0.00
Shares repurchased	0	0	0