Goodwill and Acquired Intangible Assets - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Amortization of acquired intangible assets	$ 9,655	$ 12,231	$ 10,788
Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Other acquired intangible assets estimated useful lives	2 years
Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Other acquired intangible assets estimated useful lives	10 years