Shareholders' Equity (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Shareholders' equity activity [Roll Forward]
Balance at beginning of period	$ 15,495	$ 16,298
Stock plans	126	129
Payments of dividends to shareholders	(154)	(153)
Other	12	(7)
Comprehensive income (loss)	(2,419)	(644)
Balance at end of period	13,060	15,623
Company shareholders' equity
Shareholders' equity activity [Roll Forward]
Balance at beginning of period	15,462	16,267
Stock plans	126	129
Payments of dividends to shareholders	(154)	(153)
Other	(6)	(6)
Comprehensive income (loss)	(2,413)	(646)
Balance at end of period	13,015	15,591
Noncontrolling interest in consolidated subsidiaries
Shareholders' equity activity [Roll Forward]
Balance at beginning of period	33	31
Stock plans	0	0
Payments of dividends to shareholders	0	0
Other	18	(1)
Comprehensive income (loss)	(6)	2
Balance at end of period	$ 45	$ 32