Revenue Recognition - Transition Disclosures, Statement of Financial Position (Details) - USD ($) $ in Millions	Mar. 31, 2018	Jan. 01, 2018	Dec. 31, 2017		Mar. 31, 2017	Dec. 31, 2016
Assets:
Notes and accounts receivable - trade (net of allowances)	$ 7,778	$ 8,295	$ 8,928
Deferred costs (current)	2,413		1,820	[1]
Prepaid expenses and other current assets	2,573		1,860	[1],[2]
Deferred taxes	5,111		4,862
Deferred costs (noncurrent)	2,593		2,136	[1]
Investments and sundry assets	2,942		2,783	[1]
Total assets	125,285		125,356
Liabilities:
Taxes	2,918		4,219
Deferred income (current)	13,059	11,493	11,552
Deferred income (noncurrent)	3,852	$ 3,758	3,746
Total liabilities	106,995		107,631
Equity:
Retained earnings	156,371		153,126
Total stockholders' equity	18,290		17,725		$ 18,448	$ 18,392
Total liabilities and stockholders' equity	125,285		$ 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)	640
Deferred costs (current)	(340)
Prepaid expenses and other current assets	(582)
Deferred taxes	186
Deferred costs (noncurrent)	(351)
Total assets	(447)
Liabilities:
Deferred income (current)	89
Deferred income (noncurrent)	(8)
Total liabilities	81
Equity:
Retained earnings	(528)
Total stockholders' equity	(528)
Total liabilities and stockholders' equity	(447)
Accounting Standards Update 2014-09, Revenue from Contracts with Customers | Adjusted amounts under prior GAAP
Assets:
Notes and accounts receivable - trade (net of allowances)	8,418
Deferred costs (current)	2,073
Prepaid expenses and other current assets	1,991
Deferred taxes	5,297
Deferred costs (noncurrent)	2,242
Investments and sundry assets	2,942
Total assets	124,838
Liabilities:
Taxes	2,918
Deferred income (current)	13,148
Deferred income (noncurrent)	3,844
Total liabilities	107,076
Equity:
Retained earnings	155,843
Total stockholders' equity	17,762
Total liabilities and stockholders' equity	$ 124,838

[1] Recast to conform to current period presentation.

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