Accounting Changes (Details) $ / shares in Units, $ in Millions	1 Months Ended	3 Months Ended		12 Months Ended
	Jan. 31, 2017 item	Mar. 31, 2017 USD ($) $ / shares	Mar. 31, 2016 USD ($) $ / shares	Dec. 31, 2018 USD ($)	Dec. 31, 2016 USD ($)	Jan. 01, 2017 USD ($)
Accounting Changes
Operating lease commitments					$ 6,900
Sales-type lease revenue recognized based on use of residual value guarantee insurance					220
Impact to cash flows		$ 2,270	$ 6,668
Investments and sundry assets		4,549			4,585
Prepaid expenses and other current assets		4,715			4,564
Deferred tax assets		6,457			5,224
Retained earnings		153,292			$ 152,759
Provision for/(benefit from) income taxes		(329)	(983)
Income from continuing operations		1,753	2,016
Net income		$ 1,750	$ 2,014
Earnings per share, basic (in dollars per share) | $ / shares		$ 1.86	$ 2.09
Earnings per share, diluted (in dollars per share) | $ / shares		$ 1.85	$ 2.09
Accounting Standards Update 2016-16, Intra-Entity Transfers of Assets Other Than Inventory | Early adoption
Accounting Changes
Investments and sundry assets						$ (95)
Prepaid expenses and other current assets						(47)
Deferred tax assets						244
Retained earnings						$ 102
Number of transactions within scope of new guidance | item	1
Provision for/(benefit from) income taxes		$ (582)
Income from continuing operations		582
Net income		$ 582
Earnings per share, basic (in dollars per share) | $ / shares		$ 0.62
Earnings per share, diluted (in dollars per share) | $ / shares		$ 0.61
Accounting Standards Update 2014-09, Revenue from Contracts with Customers | Expected
Accounting Changes
Impact to cash flows				$ 0