Differences Between Statutory Income Tax Rate and Effective Income Tax Rate (Detail)	3 Months Ended		9 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Statutory income tax rate	21.00%	21.00%	21.00%	21.00%
Excess tax benefits from stock-based awards	(2.40%)	(0.50%)	(4.80%)	(6.30%)
Credits	(1.70%)	(1.60%)	(1.70%)	(1.60%)
State taxes, net	4.20%	3.30%	4.20%	3.30%
Permanent differences	2.10%	1.80%	2.10%	1.80%
Foreign tax credit	(0.30%)	4.00%	(0.30%)	2.70%
Other	0.50%	0.70%	0.90%	0.40%
Effective tax rate	23.40%	28.70%	21.40%	21.30%