Leases (Schedule of Additional Lease Information) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Cash outflows for lease liabilities:
Operating cash flows, Finance lease	$ 7	$ 7
Weighted average remaining lease term (years), Finance lease	7 years	8 years
Weighted average discount rate, Finance lease	4.20%	4.20%
Operating cash flows, Operating lease	$ 2	$ 2
Investing cash flows, Operating lease	$ 8	41
Right-of-use assets obtained in exchange for new lease liabilities, Operating lease		$ 3
Weighted average remaining lease term (years), Operating lease	4 years 1 month 6 days	2 years 2 months 12 days
Weighted average discount rate, Operating lease	2.90%	3.20%