CONSOLIDATED STATEMENT OF SHAREHOLDERS' EQUITY Statement - USD ($) shares in Millions, $ in Millions	Total	Common Stock [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Noncontrolling Interest [Member]
Beginning balance (in shares) at Mar. 31, 2025		98.3
Beginning balance at Mar. 31, 2025	$ 6,615.8	$ 4,420.4	$ 2,475.3	$ (292.3)	$ 12.4
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	178.0		177.4		0.6
Other comprehensive income	221.8			221.8
Repurchases of ordinary shares (in shares)		0.1
Repurchases of ordinary shares	(10.6)	$ (10.6)	0.0
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures		0.2
Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures	21.2	$ 21.2
Dividends, Common Stock, Cash	(56.2)		(56.2)
Other changes in noncontrolling interest	(0.1)				(0.1)
Ending balance at Jun. 30, 2025	$ 6,969.9	$ 4,431.0	2,596.5	(70.5)	12.9
Ending balance (in shares) at Jun. 30, 2025		98.4
Beginning balance (in shares) at Mar. 31, 2026	97.8	97.8
Beginning balance at Mar. 31, 2026	$ 7,197.2	$ 4,280.9	3,015.9	(113.1)	13.6
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	201.0		200.1		0.9
Other comprehensive income	(14.1)			(14.1)
Repurchases of ordinary shares (in shares)		0.5
Repurchases of ordinary shares	(115.5)	$ (115.5)
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures		0.2
Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures	14.1	$ 14.1
Dividends, Common Stock, Cash	(61.4)		(61.4)
Ending balance at Jun. 30, 2026	$ 7,221.3	$ 4,179.5	$ 3,154.5	$ (127.3)	$ 14.5
Ending balance (in shares) at Jun. 30, 2026	97.5	97.5