CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (Parenthetical) $ in Millions	3 Months Ended
	Mar. 31, 2019 USD ($) Dividend $ / shares	Mar. 31, 2018 USD ($) Dividend $ / shares	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Statement of Stockholders' Equity [Abstract]
Dividends declared per common share (in dollars per share) | $ / shares	$ 0.85	$ 0.82
Accumulated other comprehensive income (loss), cumulative translation losses	$ (3,134)	$ (2,832)	$ (3,155)	$ (2,927)
Accumulated other comprehensive income (loss), unrecognized retirement plan and other retiree benefit costs	$ 1,026	$ 1,062	$ 1,038	$ 923
Number of dividends declared per quarter (in dividends) | Dividend	2	2