Income Taxes - Tax Effected Operating Loss, Capital Loss, and Tax Credit Carryovers (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Income tax
Net UTB impacting the effective tax rate	$ 1,155		$ 1,155		$ 1,178
Deferred tax assets valuation allowance	$ 124		$ 124		158
Effective tax rate (as a percent)	21.40%	19.30%	20.00%	19.70%
Increase in effective income tax rate from prior reporting period to current reporting period (as a percent)	2.10%
Decrease in unrecognized tax benefits due to resolution of a lawsuit			$ 52
Reinvested earnings that may be repatriated from non-U.S. subsidiaries	$ 5,000		5,000
Indefintely undistributed earnings of non-U.S. subsidiaries	$ 9,000		$ 9,000		$ 14,000