Accounting Changes (Details) $ / shares in Units, $ in Millions	1 Months Ended	3 Months Ended			6 Months Ended		12 Months Ended
	Jan. 31, 2017 item	Jun. 30, 2017 USD ($) $ / shares	Mar. 31, 2017 USD ($)	Jun. 30, 2016 USD ($) $ / shares	Jun. 30, 2017 USD ($) $ / shares	Jun. 30, 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					$ 3,870	$ 2,330
Investments and sundry assets		$ 4,759			4,759			4,585
Prepaid expenses and other current assets		4,155			4,155			4,564
Deferred tax assets		6,812			6,812			5,224
Retained earnings		154,234			154,234			$ 152,759
Provision for/(benefit from) income taxes		111	$ (329)	$ 544	(218)	(439)
Income from continuing operations		2,332		2,505	4,085	4,521
Net income		$ 2,331		$ 2,504	$ 4,082	$ 4,518
Earnings per share, basic (in dollars per share) | $ / shares		$ 2.49		$ 2.62	$ 4.35	$ 4.71
Earnings per share, diluted (in dollars per share) | $ / shares		$ 2.48		$ 2.61	$ 4.32	$ 4.69
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)		$ (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					$ 0.62
Accounting Standards Update 2014-09, Revenue from Contracts with Customers | Expected
Accounting Changes
Impact to cash flows							$ 0