Investments in Debt and Equity Securities (Details 2) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Available-for-sale Securities, Continuous Unrealized Loss Position
Less than 12 months - Fair Value	$ 207	$ 15
Less than 12 months - Unrealized losses	2	0
12 months or more - Fair Value	7	9
12 months or more - Unrealized losses	0	0
Total - Fair Value	214	24
Total - Unrealized losses	2	0
Corporate bonds
Available-for-sale Securities, Continuous Unrealized Loss Position
Less than 12 months - Fair Value	118	13
Less than 12 months - Unrealized losses	1	0
12 months or more - Fair Value	5	4
12 months or more - Unrealized losses	0	0
Total - Fair Value	123	17
Total - Unrealized losses	1	0
U.S. governmental agency mortgage-backed securities
Available-for-sale Securities, Continuous Unrealized Loss Position
Less than 12 months - Fair Value	89	2
Less than 12 months - Unrealized losses	1	0
12 months or more - Fair Value	2	5
12 months or more - Unrealized losses	0	0
Total - Fair Value	91	7
Total - Unrealized losses	$ 1	$ 0