Investments (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Short-term investments:
Total short-term investments	$ 160	$ 779
Long-term investments:
Restricted investments		414
Long-term Investments, Total	429	17
Short-term Investments [Member]
Short-term investments:
Equity investment security	27	26
Held-to-maturity investment securities	130	287
Time Deposits	3	466
Long-term investments:
Restricted investments		414
Long-term investments [Member]
Long-term investments:
Equity and Cost Method Investments	38	$ 17
Restricted investments	$ 391