Consolidated Statements of Shareholder's Equity - USD ($) $ in Millions	Total	Capital stock	Additional paid-in capital	Accumulated other comprehensive (loss) income	Retained earnings
Balance at Mar. 31, 2022	$ 18,101	$ 915	$ 2	$ (21)	$ 17,205
Net income	653	0	0	0	653
Other comprehensive income (loss), net of tax	(46)	0	0	(46)	0
Balance at Dec. 31, 2022	18,708	915	2	(67)	17,858
Balance at Sep. 30, 2022	18,341	915	2	(70)	17,494
Net income	364	0	0	0	364
Other comprehensive income (loss), net of tax	3	0	0	3	0
Balance at Dec. 31, 2022	18,708	915	2	(67)	17,858
Balance at Mar. 31, 2023	16,509	915	2	(57)	15,649
Net income	1,318	0	0	0	1,318
Other comprehensive income (loss), net of tax	0	0	0	0	0
Balance at Dec. 31, 2023	17,827	915	2	(57)	16,967
Balance at Sep. 30, 2023	17,194	915	2	(87)	16,364
Net income	603	0	0	0	603
Other comprehensive income (loss), net of tax	30	0	0	30	0
Balance at Dec. 31, 2023	$ 17,827	$ 915	$ 2	$ (57)	$ 16,967