CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (Parenthetical)	1 Months Ended						12 Months Ended
	Sep. 30, 2023 $ / shares	Sep. 30, 2023 SFr / shares	Sep. 30, 2022 $ / shares	Sep. 30, 2022 SFr / shares	Sep. 30, 2021 $ / shares	Sep. 30, 2021 SFr / shares	Mar. 31, 2024 $ / shares	Mar. 31, 2023 $ / shares	Mar. 31, 2022 $ / shares
Statement of Stockholders' Equity [Abstract]
Cash dividends per share (in dollars per share) | (per share)	$ 1.16	SFr 1.06	$ 0.98	SFr 0.96	$ 0.95	SFr 0.87	$ 1.19	$ 1.00	$ 0.95