Letters of Credit (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Line of Credit Facility [Line Items]
Short-term Debt	$ 0	$ 179
Letter of Credit [Member]
Line of Credit Facility [Line Items]
Short-term Debt	$ 9	$ 10
Letter of Credit [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Expiration Period	1 year
Bilateral Credit Agreement [Member] | Letter of Credit [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 75
Short-term Debt	$ 45