Fair Value Measurements Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Net unrealized loss on investment of equity securities	$ 964		$ 1,046
Net unrealized gain on investment of equity securities		$ 58		$ 312
Short-term and long-term debt	29,290		29,290		$ 24,593
Market value | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term and long-term debt	33,300		33,300		27,300
Carrying value | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term and long-term debt	$ 29,300		$ 29,300		$ 24,600