Goodwill and Acquired Intangible Assets - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Increase (decrease) in goodwill		$ 2,800
Amortization of acquired intangible assets	$ 12,231	10,788	$ 16,438
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
Arconics [Member]
Finite-Lived Intangible Assets [Line Items]
Change in goodwill related to an acquisition		3,800
Increase in other intangible assets related to acquisition		$ 19,300