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, 2017	$ 9,524	$ 915	$ 2	$ 25	$ 8,582
Net income	3,410	0	0	0	3,410
Other comprehensive income (loss), net of tax	(54)	0	0	(54)	0
Balance at Mar. 31, 2018	12,880	915	2	(29)	11,992
Cumulative-effect of change in accounting policy	(110)	0	0	12	(122)
Net income	795	0	0	0	795
Other comprehensive income (loss), net of tax	20	0	0	20	0
Dividends, net of tax	(7)	0	0	0	(7)
Balance at Mar. 31, 2019	13,578	915	2	3	12,658
Net income	913	0	0	0	913
Other comprehensive income (loss), net of tax	12	0	0	12	0
Balance at Mar. 31, 2020	$ 14,503	$ 915	$ 2	$ 15	$ 13,571