Shareholders' Equity (Details) - USD ($) $ in Millions		3 Months Ended			6 Months Ended
		Jun. 30, 2017		Jun. 30, 2016	Jun. 30, 2017		Jun. 30, 2016	Jan. 01, 2017
Shareholders' equity activity [Roll Forward]
Balance at beginning of period					$ 9,448		$ 15,495
Effect of early adoption of income tax consequences of intra-entity transfer of assets other than inventory		$ (384)	[1]		(384)	[1]		$ (384)
Stock plans					239		244
Payments of dividends to shareholders					(312)		(309)
Other					(38)		(32)
Comprehensive income (loss)		30		$ (3,202)	0		(5,621)
Balance at end of period		8,953		9,777	8,953		9,777
Company shareholders' equity
Shareholders' equity activity [Roll Forward]
Balance at beginning of period					9,409		15,462
Effect of early adoption of income tax consequences of intra-entity transfer of assets other than inventory	[1]	(384)			(384)
Stock plans					239		244
Payments of dividends to shareholders					(312)		(309)
Other					(35)		(45)
Comprehensive income (loss)							(5,618)
Balance at end of period		8,917		9,734	8,917		9,734
Noncontrolling interest in consolidated subsidiaries
Shareholders' equity activity [Roll Forward]
Balance at beginning of period					39		33
Effect of early adoption of income tax consequences of intra-entity transfer of assets other than inventory	[1]	0			0
Stock plans					0		0
Payments of dividends to shareholders					0		0
Other					(3)		13
Comprehensive income (loss)							(3)
Balance at end of period		$ 36		$ 43	$ 36		$ 43

[1] Represents a cumulative-effect adjustment to retained earnings upon our adoption of a new accounting standards update on the income tax consequences of intra-entity transfers of assets other than inventory which was effective January 1, 2017. See Note 8 for further information.