Consolidated Statements of Shareholder's Equity - USD ($) $ in Millions	Total	Capital stock	Additional paid-in capital	Accumulated other comprehensive income (loss)	Retained earnings
Balance at Mar. 31, 2021	$ 15,595	$ 915	$ 2	$ 8	$ 14,670
Net income	1,543	0	0	0	1,543
Other comprehensive (loss) income	7	0	0	7	0
Balance at Sep. 30, 2021	17,145	915	2	15	16,213
Balance at Jun. 30, 2021	16,525	915	2	17	15,591
Net income	622	0	0	0	622
Other comprehensive (loss) income	(2)	0	0	(2)	0
Balance at Sep. 30, 2021	17,145	915	2	15	16,213
Balance at Mar. 31, 2022	18,101	915	2	(21)	17,205
Net income	289	0	0	0	289
Other comprehensive (loss) income	(49)	0	0	(49)	0
Balance at Sep. 30, 2022	18,341	915	2	(70)	17,494
Balance at Jun. 30, 2022	18,245	915	2	(47)	17,375
Net income	119	0	0	0	119
Other comprehensive (loss) income	(23)	0	0	(23)	0
Balance at Sep. 30, 2022	$ 18,341	$ 915	$ 2	$ (70)	$ 17,494