Summary of Weighted Average Grant-Date Fair Values And Weighted Average Assumptions Used to Calculate Fair Value of Options Granted (Detail) - $ / shares	1 Months Ended		3 Months Ended		6 Months Ended
	May 31, 2021	May 31, 2020	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Valuation assumptions:
Risk-free interest rate	0.30%	0.20%
Expected option life (years)	2 years 9 months 18 days	2 years 10 months 24 days
Expected volatility	44.80%	35.50%
Stock Options
Valuation assumptions:
Weighted average grant-date fair value			$ 118.40	$ 115.99	$ 119.74	$ 103.48
Risk-free interest rate			3.32%	0.77%	3.20%	0.79%
Expected option life (years)			5 years 7 months 6 days	4 years 1 month 20 days	5 years 6 months 29 days	4 years 2 months 12 days
Expected volatility			43.49%	44.72%	43.50%	44.30%