Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Oct. 31, 2017	Oct. 31, 2016	Oct. 31, 2017	Oct. 31, 2016
Income Statement [Abstract]
Revenue	$ 53,409	$ 50,408	$ 105,567	$ 100,501
Cost of revenue	19,565	18,855	39,330	37,611
Gross profit	33,844	31,553	66,237	62,890
Operating expenses:
Sales and marketing	14,245	15,819	28,849	31,123
Research and development	10,055	9,959	20,558	21,032
General and administrative	8,013	8,051	16,598	16,310
Restructuring charges	(16)	(767)	(56)	(1,094)
Acquisition-related and other	478	120	739	296
Amortization of acquired intangible assets	310	310	619	619
Total operating expenses	33,117	35,026	67,419	70,474
Operating income (loss)	727	(3,473)	(1,182)	(7,584)
Other income (expense), net:
Interest income	56	153	142	295
Interest expense	(252)	(459)	(646)	(948)
Other income (expense)	(366)	(263)	(341)	(775)
Total other expense, net	(562)	(569)	(845)	(1,428)
Income (loss) before income taxes	165	(4,042)	(2,027)	(9,012)
Income tax expense	220	92	344	227
Net loss	$ (55)	$ (4,134)	$ (2,371)	$ (9,239)
Net loss per share:
Basic and diluted loss per share	$ 0.00	$ (0.05)	$ (0.03)	$ (0.11)
Basic and diluted weighted average number of shares outstanding	85,630	82,930	85,147	82,572