Share-Based Compensation Share-Based Compensation (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2024
Share-based Compensation Arrangement by Share-based Payment Award [Line Item]
Remaining shares available for grant	1,300,000
Weighted-average assumptions used for options granted:
Risk-free interest rate	4.02%	4.03%
Expected life of options	6 years 1 month 6 days	6 years
Exptected dividend yield of stock	1.10%	1.11%
Expected volatility of stock	28.69%	28.19%
Estimated forfeiture rate	1.92%	2.21%
Summary of share option activity:
Outstanding at the beginning of the period	1,716,867
Granted	214,844
Exercised	(18,162)
Outstanding at the end of the period	1,912,986
Exercisable at the end of the period	1,406,339
Weighted average exercise price:
Outstanding at the beginning of the period	$ 204.51
Granted	230.74
Exercised	70.81
Outstanding at the end of the period	208.82
Exercisable at the end of the period	$ 196.38
Average Remaining Contractual Term, Outstanding at the end of the period	5 years 10 months 24 days
Aggregate Intrinsic Value, Outstanding at the end of the period	$ 38.6
Average Remaining Contractual Term, Exercisable at the end of the period	4 years 10 months 24 days
Aggregate Intrinsic Value, Exercisable at the end of the period	$ 38.6
Non-vested stock options outstanding expected to vest	500,000
Ordinary shares, closing price	$ 210.57
Total intrinsic value of stock options exercised	$ 2.6	$ 9.4
Net cash proceeds from the exercise of stock options	$ 1.3	$ 9.3
Weighted average grant date fair value of stock option grants, per share	$ 60.17	$ 68.44
Summary of non-vested restricted share activity:
Unrecognized compensation cost related to nonvested share-based compensation granted	$ 85.9
Weighted Average Period For Total Compensation Expense Not Yet Recognized	1 year 7 months 6 days
Forfeited	(563)
Forfeited	$ 219.97
Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Rights, Percentage	25.00%
Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Period	4 years		3 years
Restricted Stock
Summary of non-vested restricted share activity:
Number of Restricted Shares, Non-vested at Beginning of Period	456,080
Weighted-Average Grant Date Fair Value, Non-vested at Beginning of Period	$ 226.73
Number of Restricted Shares, Granted	205,332
Weighted-Average Grant Date Fair Value, Granted	$ 209.86
Number of Restricted Shares, Vested	(198,818)
Weighted-Average Grant Date Fair Value, Vested	$ 216.80
Number of Restricted Shares, Canceled	(4,901)
Weighted-Average Grant Date Fair Value, Canceled	$ 226.90
Number of Restricted Shares, Non-vested at End of Period	457,693
Weighted-Average Grant Date Fair Value, Non-vested at End of Period	$ 223.51
Fair Value, Share-based Payment Awards, Other than Options	$ 46.1
Restricted Stock Units (RSUs)
Summary of non-vested restricted share activity:
Number of Restricted Shares, Non-vested at Beginning of Period	30,289
Number of Restricted Shares, Granted	12,495
Number of Restricted Shares, Vested	(12,741)
Number of Restricted Shares, Canceled	(207)
Number of Restricted Shares, Non-vested at End of Period	29,836