Goodwill and Purchased Intangibles Assets - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Change in carrying amount of goodwill			$ 0
Amortization expense	$ 200,000	$ 200,000	$ 1,000,000	$ 700,000