Income Taxes - Tax Effected Operating Loss, Capital Loss, and Tax Credit Carryovers (Details) - USD ($) $ in Millions		3 Months Ended	12 Months Ended
	Jan. 01, 2019	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income tax
Net UTB impacting the effective tax rate		$ 526	$ 1,178	$ 655	$ 526
Interest and penalties related to unrecognized tax benefits, expense (benefit) recognized on a gross basis			33	12	$ 20
Interest and penalties related to unrecognized tax benefits, accrued on a gross basis			102	69
Deferred tax assets valuation allowance			$ 158	$ 67
Effective tax rate (as a percent)			19.80%	23.40%	35.50%
Increase (decrease) in effective income tax rate from prior reporting period to current reporting period (as a percent)			(3.60%)	(12.10%)
Statutory U.S. tax rate			21.00%	21.00%	35.00%
Provisional income tax expense (benefit) from enactment of Tax Cuts and Jobs Act of 2017		$ 762
Tax Cuts and Jobs Act of 2017 measurement period adjustment				$ 176
Unrecognized tax benefits to be recognized within next 12 months			$ 50
Period of time over which TCJA transition tax on certain unrepatriated earnings of foreign subsidiaries may be paid				8 years
Tax Cuts and Jobs Act of 2017 transition tax in current accrued income taxes payable			33
Tax Cuts and Jobs Act of 2017 transition tax long term income taxes payable			$ 653	$ 649
Retained Earnings | ASU 2018-02 Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income
Income tax
Tax Cuts and Jobs Act of 2017, Reclassification from AOCI to Retained Earnings, Tax Effect	$ 900
Total Accumulated Other Comprehensive Income (Loss) | ASU 2018-02 Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income
Income tax
Tax Cuts and Jobs Act of 2017, Reclassification from AOCI to Retained Earnings, Tax Effect	$ 900