Earnings Per Share, Share Repurchases and Dividends on Common Stock (Unaudited) (Details 1) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016	Sep. 16, 2015	Dec. 04, 2014
December 2014 Share Repurchase Program Original Authorization
Share Repurchase [Line Items]
Amount Authorized						$ 3,000
Shares Retired				18.0
Average Cost Per Share				$ 166.70
Shares Repurchased	0.0	1.4
September 2015 Share Repurchase Program Original Authorization
Share Repurchase [Line Items]
Amount Authorized					$ 4,000
Shares Retired			6.8
Average Cost Per Share			$ 220.37
Shares Repurchased	0.9	0.1
Share Repurchases - Notes to Table
Shares repurchased amount			$ 1,500
Amount remaining under authorization for share repurchases	$ 2,500		$ 2,500