Debt (Fair Value) (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Proceeds from Sale of Securities, Operating Activities	$ 45
Senior Notes
Debt Instrument [Line Items]
Fair value of long-term debt		$ 15,250	$ 15,360