Revenue Recognition - Transition Disclosures, Statement of Financial Position (Details) - USD ($) $ in Millions	Jun. 30, 2018	Jan. 01, 2018	Dec. 31, 2017		Jun. 30, 2017	Dec. 31, 2016
Assets:
Notes and accounts receivable - trade (net of allowances)	$ 7,445	$ 8,295	$ 8,928
Deferred costs (current)	2,344		1,820	[1]
Prepaid expenses and other current assets	2,443		1,860	[1],[2]
Deferred taxes	4,689		4,862
Deferred costs (noncurrent)	2,613		2,136	[1]
Investments and sundry assets	2,518		2,783	[1]
Total assets	121,622		125,356
Liabilities:
Taxes	2,780		4,219
Deferred income (current)	11,752	11,493	11,552
Deferred income (noncurrent)	3,718	3,758	3,746
Total liabilities	102,974		107,631
Equity:
Retained earnings	157,349		153,126
AOCI	(28,290)		(26,592)
Total stockholders' equity	18,648		17,725		$ 18,544	$ 18,392
Total liabilities and stockholders' equity	121,622		$ 125,356
Accounting Standards Update 2014-09, Revenue from Contracts with Customers | Adjustments to convert to prior GAAP
Assets:
Notes and accounts receivable - trade (net of allowances)	582
Deferred costs (current)	(382)
Prepaid expenses and other current assets	(515)
Deferred taxes	187	(184)
Deferred costs (noncurrent)	(332)
Total assets	(461)
Liabilities:
Deferred income (current)	57
Deferred income (noncurrent)	(7)
Total liabilities	50
Equity:
Retained earnings	(530)	$ 524
AOCI	18
Total stockholders' equity	(512)
Total liabilities and stockholders' equity	(461)
Accounting Standards Update 2014-09, Revenue from Contracts with Customers | Adjusted amounts under prior GAAP
Assets:
Notes and accounts receivable - trade (net of allowances)	8,027
Deferred costs (current)	1,961
Prepaid expenses and other current assets	1,928
Deferred taxes	4,876
Deferred costs (noncurrent)	2,281
Investments and sundry assets	2,518
Total assets	121,161
Liabilities:
Taxes	2,780
Deferred income (current)	11,809
Deferred income (noncurrent)	3,712
Total liabilities	103,024
Equity:
Retained earnings	156,819
AOCI	(28,271)
Total stockholders' equity	18,136
Total liabilities and stockholders' equity	$ 121,161

[1] Recast to conform to current period presentation.

[2] Recast to reflect adoption of the FASB guidance on restricted cash.