Financial Instruments (Non-Marketable Equity Securities) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Fair Value Disclosures [Abstract]
Unrealized gains	$ 189	$ 962	$ 545	$ 1,418
Unrealized losses (including impairment)	(98)	(72)	(1,395)	(138)
Total unrealized gain (loss) for non-marketable equity securities	$ 91	$ 890	$ (850)	$ 1,280