Valuation of Debt and Equity Investments and Certain Liabilities - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Credit losses related to available-for-sale investments	$ 0	$ 0	$ 0
Proceeds from sales, redemptions and maturities of short-term available-for-sale securities	2,309,000,000	6,708,000,000	4,095,000,000
Net gains (losses) from equity method investments	32,000,000	5,000,000	4,000,000
Realized gains from sale of equity method investments	29,000,000	11,000,000	$ 6,000,000
Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets fair value	0	0
Total liabilities fair value	0	0
Fair Value, Measurements, Recurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets fair value	5,213,000,000	4,229,000,000
Total liabilities fair value	$ 298,000,000	$ 246,000,000