Financial Instruments (Gains and Losses on Equity Securities) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Equity Securities, FV-NI, Gain (Loss), Alternative [Abstract]
Net gain (loss) on equity securities sold during the period	$ 1,339	$ (301)
Net unrealized gain (loss) on equity securities held as of the end of the period	4,253	2,950
Total gain (loss) recognized in other income (expense), net	$ 5,592	$ 2,649	$ 5,460