Debt (Schedule of Short-term Debt) (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Short-term Debt [Line Items]
Demand notes	$ 0	$ 2,136
Total short-term borrowings	$ 0	$ 2,136
Weighted average interest rate	0.00%	0.30%
Unsecured debt
Short-term Debt [Line Items]
Demand notes	$ 0	$ 2,136
Total short-term borrowings	0	2,136
Secured debt
Short-term Debt [Line Items]
Demand notes	0	0
Total short-term borrowings	$ 0	$ 0