Earnings Per Share, Share Repurchases and Dividends on Common Stock (Unaudited) (Details 1) - September 2015 Share Repurchase Program Original Authorization - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		24 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018	Sep. 16, 2015
Share Repurchase [Line Items]
Amount Authorized				$ 4,000
Shares Retired			7.4
Average Cost Per Share			$ 222.93
Shares Repurchased	0.0	0.9
Share Repurchases - Notes to Table
Shares repurchased amount			$ 1,700
Amount remaining under authorization for share repurchases	$ 2,300		$ 2,300