Investments in Debt and Equity Securities (Details 2) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Available-for-sale Securities, Continuous Unrealized Loss Position
Less than 12 months - Fair Value	$ 234	$ 15
Less than 12 months - Unrealized losses	3	0
12 months or more - Fair Value	5	9
12 months or more - Unrealized losses	0	0
Total - Fair Value	239	24
Total - Unrealized losses	3	0
Corporate bonds
Available-for-sale Securities, Continuous Unrealized Loss Position
Less than 12 months - Fair Value	154	13
Less than 12 months - Unrealized losses	2	0
12 months or more - Fair Value	4	4
12 months or more - Unrealized losses	0	0
Total - Fair Value	158	17
Total - Unrealized losses	2	0
U.S. governmental agency mortgage-backed securities
Available-for-sale Securities, Continuous Unrealized Loss Position
Less than 12 months - Fair Value	80	2
Less than 12 months - Unrealized losses	1	0
12 months or more - Fair Value	1	5
12 months or more - Unrealized losses	0	0
Total - Fair Value	81	7
Total - Unrealized losses	$ 1	$ 0