v3.19.3.a.u2
Financial Instruments (Carrying Amount of Equity Securities) (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Fair Value Disclosures [Abstract]    
Total sale price $ 3,134 $ 1,965
Total initial cost 858 515
Cumulative net gains 2,276 1,450
Total initial cost, Marketable Securities 1,935 1,168
Cumulative net gain, Marketable Securities 1,361 54
Carrying value, Marketable Securities 3,296 1,222
Total initial cost, Non-Marketable Securities 8,297 8,168
Cumulative net gain, Non-Marketable Securities 3,056 4,107
Carrying value, Non-Marketable Securities 11,353 12,275
Total initial cost 10,232 9,336
Cumulative net gain 4,417 4,161
Carrying value 14,649 13,497
Cumulative net gain 3,500 4,300
Unrealized losses (including impairment) $ 445 $ 178