Revenue from Contracts with Customers - Summary of Impact of Adoption of ASC 606 on Consolidated Balance Sheet and Consolidated Statements of Net Income and Comprehensive Income (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Apr. 01, 2018	Mar. 31, 2018
ASSETS
Accounts receivable, net		$ 85,548		$ 85,548			$ 84,962
Contract assets		10,253		10,253
Income taxes receivable		5,976		5,976			8,122
Prepaid expenses and other current assets		16,987		16,987			17,180
Deferred income taxes, net		6,264		6,264			9,219
Contract assets, net of current		2,942		2,942
Other assets		29,226		29,226			18,795
LIABILITIES
Contract liabilities		50,023		50,023			54,079
Accrued compensation and related benefits		18,885		18,885			27,910
Other current liabilities		43,883		43,883			48,317
Contract liabilities, net of current							1,173
Shareholders' equity:
Retained earnings	[1]	102,869		102,869			$ 78,708
Revenues:
Total revenues		130,321	$ 132,607	263,521	$ 263,529
Total cost of revenue		61,118	58,755	122,969	117,924
Gross profit		69,203	73,852	140,552	145,605
Operating expenses:
Selling, general and administrative		34,229	40,977	78,865	83,954
Research and development costs, net		18,371	19,527	40,499	39,516
Amortization of acquired intangible assets		1,121	2,012	2,289	4,059
Total operating expenses		53,721	62,516	121,653	127,529
Income from operations		15,482	11,336	18,899	18,076
Interest and other income, net		(492)		(819)
Income before provision for income taxes		14,990	10,523	18,080	16,573
Provision for income taxes		1,896	2,493	2,338	4,647
Net income		13,094	$ 8,030	15,742	$ 11,926
Recurring
Revenues:
Total revenues		116,317		236,324
Software, Hardware, and Other Non-recurring
Revenues:
Total revenues		14,004		27,197
Adoption of ASC 606
ASSETS
Accounts receivable, net						$ 87,342
Contract assets						13,446
Prepaid expenses and other current assets						16,957
Deferred income taxes, net						6,335
Contract assets, net of current						2,731
Other assets						25,474
LIABILITIES
Contract liabilities						58,253
Accrued compensation and related benefits						28,655
Other current liabilities						58,281
Shareholders' equity:
Retained earnings						87,127
Adoption of ASC 606 | ASC 606 Transition Adjustments
ASSETS
Accounts receivable, net		2,496		2,496		2,380
Contract assets		(10,253)		(10,253)		13,446
Income taxes receivable		997		997
Prepaid expenses and other current assets		(2,190)		(2,190)		(223)
Deferred income taxes, net		2,884		2,884		(2,884)
Contract assets, net of current		(2,942)		(2,942)		2,731
Other assets		(6,773)		(6,773)		6,679
LIABILITIES
Contract liabilities		2,911		2,911		4,174
Accrued compensation and related benefits		(6)		(6)		745
Other current liabilities		(8,171)		(8,171)		9,964
Contract liabilities, net of current		1,030		1,030		(1,173)
Shareholders' equity:
Retained earnings		(11,511)		(11,511)		$ 8,419
Revenues:
Total revenues		(889)		(843)
Total cost of revenue		52		94
Gross profit		(941)		(937)
Operating expenses:
Selling, general and administrative		1,957		3,152
Total operating expenses		1,957		3,152
Income from operations		(2,898)		(4,089)
Income before provision for income taxes		(2,898)		(4,089)
Provision for income taxes		(751)		(997)
Net income		(2,147)		(3,092)
Adoption of ASC 606 | ASC 606 Transition Adjustments | Recurring
Revenues:
Total revenues		(793)		(106)
Adoption of ASC 606 | ASC 606 Transition Adjustments | Software, Hardware, and Other Non-recurring
Revenues:
Total revenues		(96)		(737)
Adoption of ASC 606 | Calculated under Revenue Guidance in Effect before Topic 606
ASSETS
Accounts receivable, net		88,044		88,044
Income taxes receivable		6,973		6,973
Prepaid expenses and other current assets		14,797		14,797
Deferred income taxes, net		9,148		9,148
Other assets		22,453		22,453
LIABILITIES
Contract liabilities		52,934		52,934
Accrued compensation and related benefits		18,879		18,879
Other current liabilities		35,712		35,712
Contract liabilities, net of current		1,030		1,030
Shareholders' equity:
Retained earnings		91,358		91,358
Revenues:
Total revenues		129,432		262,678
Total cost of revenue		61,170		123,063
Gross profit		68,262		139,615
Operating expenses:
Selling, general and administrative		36,186		82,017
Research and development costs, net		18,371		40,499
Amortization of acquired intangible assets		1,121		2,289
Total operating expenses		55,678		124,805
Income from operations		12,584		14,810
Interest and other income, net		(492)		(819)
Income before provision for income taxes		12,092		13,991
Provision for income taxes		1,145		1,341
Net income		10,947		12,650
Adoption of ASC 606 | Calculated under Revenue Guidance in Effect before Topic 606 | Recurring
Revenues:
Total revenues		115,524		236,218
Adoption of ASC 606 | Calculated under Revenue Guidance in Effect before Topic 606 | Software, Hardware, and Other Non-recurring
Revenues:
Total revenues		$ 13,908		$ 26,460

[1] Includes cumulative effect adjustment related to the adoption of ASC 606, as defined in Note 1. See Note 1 for additional details.