Goodwill and Acquired Intangible Assets - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Finite-Lived Intangible Assets [Line Items]
Amortization of acquired intangible assets	$ 2,435	$ 3,320	$ 4,888	$ 6,580
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