Earnings Per Share, Share Repurchases and Dividends on Common Stock (Unaudited) (Details 2) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	1 Months Ended				2 Months Ended		3 Months Ended		6 Months Ended
	May 31, 2019	May 31, 2018	Jan. 31, 2018	May 31, 2017	Jan. 04, 2019	Dec. 31, 2018	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Oct. 29, 2018
Equity, Class of Treasury Stock [Line Items]
Accelerated Share Repurchase						$ 1,000
Accelerated Share Repurchases, Payment											$ 1,000
Accelerated Share Repurchase Initial Receipt Shares											3.0
Accelerated Share Repurchase Initial Receipt Monetary											$ 800
Accelerated Share Repurchase Final Receipt Shares					0.9
Accelerated Share Repurchases, Final Price Paid Per Share					$ 260.32
Earnings Per Share, Basic and Diluted [Abstract]
Common stock dividends per share, declared (in dollars per share)	$ 1.32	$ 1.20	$ 1.10	$ 1.00			$ 1.32	$ 1.20	$ 2.52	$ 2.30
Increase in quarterly common stock dividend (percent)	10.00%	9.00%	10.00%