Presentation and Summary of Significant Accounting Policies - Summary of Effect of Adopting Topic 606 on Condensed Consolidated Statement of Operations (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended								12 Months Ended
		Apr. 30, 2019	Jan. 31, 2019	Oct. 31, 2018	Jul. 31, 2018	Apr. 30, 2018	Jan. 31, 2018	Oct. 31, 2017	Jul. 31, 2017	Apr. 30, 2019	Apr. 30, 2018	Apr. 30, 2017
Revenues:
Total revenues		$ 26,271	$ 27,003	$ 28,033	$ 27,399	$ 29,363	$ 30,117	$ 26,337	$ 26,886	$ 108,706	$ 112,703	$ 106,286
Cost of revenues:
Cost of revenues										51,966	50,000	51,084
Gross margin		14,282	14,039	14,667	13,752	16,426	17,046	14,006	15,225	56,740	62,703	55,202
Research and development										13,078	11,877	11,889
Sales and marketing										20,992	20,658	20,287
General and administrative										17,006	16,057	14,219
Amortization of acquisition-related intangibles										388	580	1,041
Total operating expenses										51,464	49,172	47,436
Operating income		1,013	2,130	1,526	607	2,463	4,204	3,242	3,622	5,276	13,531	7,766
Other income:
Interest income										2,092	1,575	1,257
Other, net										273	609	12,592
Earnings before income taxes										7,641	15,715	21,615
Income tax expense										838	3,662	6,994
Net earnings		$ 1,874	$ 2,301	$ 1,243	$ 1,385	$ 1,268	$ 5,580	$ 2,480	$ 2,725	$ 6,803	$ 12,053	$ 14,621
Earnings Per Share
Basic (in usd per share)	[1]									$ 0.22	$ 0.40	$ 0.50
Diluted (in usd per share)		$ 0.06	$ 0.07	$ 0.04	$ 0.04	$ 0.04	$ 0.18	$ 0.08	$ 0.09	$ 0.22	$ 0.40	$ 0.49
License
Revenues:
Total revenues										$ 7,126	$ 15,344	$ 15,584
Cost of revenues:
Cost of revenues										6,430	6,261	6,713
Subscription fees
Revenues:
Total revenues										14,026	8,855	4,381
Cost of revenues:
Cost of revenues										5,759	3,817	3,290
Professional services and other
Revenues:
Total revenues										42,154	44,663	43,932
Cost of revenues:
Cost of revenues										31,421	30,596	31,374
Maintenance
Revenues:
Total revenues										45,400	43,841	42,389
Cost of revenues:
Cost of revenues										8,356	$ 9,326	$ 9,707
Difference between Revenue Guidance in Effect before and after Topic 606
Revenues:
Total revenues										1,200
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09
Revenues:
Total revenues										774
Cost of revenues:
Cost of revenues										0
Gross margin										774
Research and development										0
Sales and marketing										166
General and administrative										0
Amortization of acquisition-related intangibles										0
Total operating expenses										166
Operating income										608
Other income:
Interest income										0
Other, net										0
Earnings before income taxes										608
Income tax expense										66
Net earnings										$ 542
Earnings Per Share
Basic (in usd per share)										$ 0
Diluted (in usd per share)										$ 0
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09 | License
Revenues:
Total revenues										$ 627
Cost of revenues:
Cost of revenues										0
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09 | Subscription fees
Revenues:
Total revenues										8
Cost of revenues:
Cost of revenues										0
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09 | Professional services and other
Revenues:
Total revenues										139
Cost of revenues:
Cost of revenues										0
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09 | Maintenance
Revenues:
Total revenues										0
Cost of revenues:
Cost of revenues										0
Calculated under Revenue Guidance in Effect before Topic 606
Revenues:
Total revenues										109,480
Cost of revenues:
Cost of revenues										51,966
Gross margin										57,514
Research and development										13,078
Sales and marketing										21,158
General and administrative										17,006
Amortization of acquisition-related intangibles										388
Total operating expenses										51,630
Operating income										5,884
Other income:
Interest income										2,092
Other, net										273
Earnings before income taxes										8,249
Income tax expense										904
Net earnings										$ 7,345
Earnings Per Share
Basic (in usd per share)										$ 0
Diluted (in usd per share)										$ 0
Calculated under Revenue Guidance in Effect before Topic 606 | License
Revenues:
Total revenues										$ 7,753
Cost of revenues:
Cost of revenues										6,430
Calculated under Revenue Guidance in Effect before Topic 606 | Subscription fees
Revenues:
Total revenues										14,034
Cost of revenues:
Cost of revenues										5,759
Calculated under Revenue Guidance in Effect before Topic 606 | Professional services and other
Revenues:
Total revenues										42,293
Cost of revenues:
Cost of revenues										31,421
Calculated under Revenue Guidance in Effect before Topic 606 | Maintenance
Revenues:
Total revenues										45,400
Cost of revenues:
Cost of revenues										$ 8,356

[1] Diluted per share amounts for Class A shares are shown above. Diluted per share for Class B shares under the two-class method are $0.22, $0.39 and $0.49 for the years ended April 30, 2019, 2018 and 2017, respectively. See Note 1 to the Consolidated Financial Statements.