Income Taxes - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2018	Dec. 31, 2015
Income Taxes - Narrative (Details)
Federal statutory rate			21.00%	35.00%	35.00%
Income Tax Expense (Benefit)			$ 2,339	$ 8,885	$ 3,609
Income taxes payable			(1,459)	5,497	1,010
Other accrued liabilities	$ 3,139	$ 3,370	3,139	3,370		$ 3,255
Long-term income taxes payable	5,922	6,794	5,922	6,794
Foreign Earnings Repatriated			30,400
Deferred Tax Assets, Valuation Allowance	331	162	331	162
Total Gross Unrecognized Tax Benefits	1,595	2,181	1,595	2,181	$ 1,852		$ 1,350
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	1,300	1,800	1,300	1,800
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued	154	112	154	112
Decrease in Unrecognized Tax Benefits is Reasonably Possible	100		100
Tax Cuts and Jobs Act of 2017 [Member]
Income Taxes - Narrative (Details)
Income Tax Expense (Benefit)		5,500	4
Income Tax Expense (Benefit), Continuing Operations, Adjustment of Deferred Tax (Asset) Liability		308
Taxes Payable		6,100		$ 6,100
Income taxes payable			(1,500)
Payments for Other Taxes			1,300
Long-term income taxes payable	4,600		4,600
Domestic Tax Authority [Member]
Income Taxes - Narrative (Details)
Operating Loss Carryforwards	494		494
Tax Credit Carryforward, Amount	179		179
State and Local Jurisdiction [Member]
Income Taxes - Narrative (Details)
Operating Loss Carryforwards	1,500		1,500
Tax Credit Carryforward, Amount	414		414
Transition Tax [Member] | Tax Cuts and Jobs Act of 2017 [Member]
Income Taxes - Narrative (Details)
Income Tax Expense (Benefit)		$ 5,800	$ 174
impairmentTaxEffected [Member]
Income Taxes - Narrative (Details)
Deferred Income Tax Expense (Benefit)	$ 588