Condensed Consolidated Balance Sheets (unaudited) (Parenthetical) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Dec. 31, 2023	Mar. 31, 2023
Common Stock, Shares Authorized, Unlimited [Fixed List]	Unlimited	Unlimited
Common stock, shares issued (in shares)	1,100	1,100
Common stock, shares outstanding (in shares)	1,100	1,100
Third Party
Accounts receivable, allowance for credit loss	$ 7	$ 5