Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended																12 Months Ended
	Mar. 31, 2021		Dec. 31, 2020	[1]	Sep. 30, 2020	[1]	Jun. 30, 2020	[1]	Mar. 31, 2020		Dec. 31, 2019	[1]	Sep. 30, 2019	[1]	Jun. 30, 2019	[1]	Mar. 31, 2021		Mar. 31, 2020		Dec. 31, 2019	Mar. 31, 2019
Income Taxes [Line Items]
Income tax provision	$ 16,638,000	[1]	$ 18,867,000		$ 10,702,000		$ 16,488,000		$ 7,515,000	[1]	$ 27,799,000		$ 4,287,000		$ 14,215,000		$ 62,695,000	[1]	$ 53,816,000	[1]		$ 4,344,000
Effective income tax rate																	21.80%		21.00%			1.60%
Valuation allowance	15,667,000								$ 15,170,000								$ 15,667,000		$ 15,170,000
Excess tax benefits from stock-based awards																	12,100,000		14,800,000		$ 69,300,000
Foreign tax credits																	$ 13,800,000
Potential repatriation of foreign subsidiary earnings																	100.00%
Interest and penalties on uncertain tax positions																	$ 0		$ 0		$ 0
Earliest Tax Year
Income Taxes [Line Items]
Foreign tax credits carry forwards expiration period																	2029
Federal and state research and development credit carry forwards year of expiration																	2022
Latest Tax Year
Income Taxes [Line Items]
Foreign tax credits carry forwards expiration period																	2031
Federal and state research and development credit carry forwards year of expiration																	2041
Foreign
Income Taxes [Line Items]
Net operating loss carry forwards	27,200,000																$ 27,200,000
Federal
Income Taxes [Line Items]
Research and development credit carry forwards	400,000																400,000
State
Income Taxes [Line Items]
Research and development credit carry forwards	$ 12,800,000																$ 12,800,000

[1] The income tax provision for the years ended March 31, 2021 and 2020 included excess tax benefits of $12.1 million and $14.8 million, respectively. These recognized excess tax benefits resulted from restricted stock units that vested or stock options that were exercised during the years ended March 31, 2021 and 2020.