Components of Income Tax Provision (Detail) - USD ($) $ in Thousands	3 Months Ended																12 Months Ended
	Mar. 31, 2020	[1]	Dec. 31, 2019	[1]	Sep. 30, 2019	[1]	Jun. 30, 2019	[1]	Mar. 31, 2019	[1]	Dec. 31, 2018	[1]	Sep. 30, 2018	[1]	Jun. 30, 2018	[1]	Mar. 31, 2020		Mar. 31, 2019		Mar. 31, 2018
Income Tax Disclosure [Abstract]
Income (loss) before income taxes																	$ 214,825		$ 223,340		$ 134,006
Income (loss) before income taxes, foreign																	42,000		40,020		26,431
Income (loss) before income taxes																	256,825		263,360		160,437
Current income tax provision, Federal																					752
Current income tax provision, State																	6,563		564		1,491
Current income tax provision, Foreign																	14,300		11,525		3,400
Current income tax provision																	20,863		12,089		5,643
Deferred income tax provision, Federal																	33,239		(7,153)		38,848
Deferred income tax provision, State																	1,584		(1,503)		(1,014)
Deferred income tax provision, Foreign																	(1,870)		911		4,790
Deferred income tax provision																	32,953		(7,745)		42,624
Total income tax provision	$ 7,515		$ 27,799		$ 4,287		$ 14,215		$ 24,569		$ 19,648		$ 1,706		$ (41,579)		$ 53,816	[1]	$ 4,344	[1]	$ 48,267

[1]   (2) The income tax provision for the years ended March 31, 2020 and 2019 included excess tax benefits of $14.8 million and $69.3 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, 2020 and 2019.