Income Taxes - Income from Continuing Opearations Before Income Taxes and Tax Rate Reconciliation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income from Continuing Operations Before Income Taxes
Domestic	$ 1,806	$ 1,653	$ 1,660
Foreign	1,464	1,255	1,059
Income Before Taxes	$ 3,270	$ 2,908	$ 2,719
Reconciliation Between the U.S. Federal Statutory Tax Rate and The Effective Tax Rate
U.S. federal statutory tax rate	35.00%	35.00%	35.00%
Tax effect of U.S. federal tax law change	20.10%	0.00%	0.00%
State income taxes, net of U.S. federal tax benefit	1.20%	1.30%	1.40%
Differences between U.S. federal statutory and foreign tax rates	(3.50%)	(3.60%)	(3.10%)
Nontaxable foreign interest income	(1.70%)	(2.10%)	(3.30%)
Tax effect of foreign dividends	0.90%	1.50%	2.80%
Tax relief for U.S. manufacturers	(1.40%)	(1.40%)	(1.60%)
Excess tax benefits from stock-based compensation	(1.50%)	(0.00%)	(0.00%)
Other, net	(0.70%)	(0.70%)	(1.10%)
Effective tax rate	48.40%	30.00%	30.10%