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								12 Months Ended
		Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017	Apr. 01, 2018
ASSETS
Accounts receivable, net		$ 87,459				$ 84,962				$ 87,459	$ 84,962
Contract assets		13,242								13,242
Income taxes receivable		3,682				8,122				3,682	8,122
Prepaid expenses and other current assets		20,826				17,180				20,826	17,180
Deferred income taxes, net		6,194				9,219				6,194	9,219
Contract assets, net of current		3,747								3,747
Other assets		32,478				18,795				32,478	18,795
LIABILITIES
Contract liabilities		56,009				54,079				56,009	54,079
Accrued compensation and related benefits		25,663				27,910				25,663	27,910
Other current liabilities		41,064				48,317				41,064	48,317
Contract liabilities, net of current						1,173					1,173
Shareholders' equity:
Retained earnings	[1]	111,621				78,708				111,621	78,708
Revenues:
Total revenues		134,785	$ 130,867	$ 130,321	$ 133,200	135,775	$ 131,715	$ 132,607	$ 130,922	529,173	531,019	$ 509,624
Total cost of revenue		62,057	61,671	61,118	61,851	61,977	61,634	58,755	59,169	246,697	241,535	223,134
Gross profit		72,728	69,196	69,203	71,349	73,798	70,081	73,852	71,753	282,476	289,484	286,490
Operating expenses:
Selling, general and administrative		44,710	41,304	34,229	44,636	65,709	43,563	40,977	42,977	164,879	193,226	163,623
Research and development costs, net		19,813	20,682	18,371	22,128	21,098	20,645	19,527	19,989	80,994	81,259	78,341
Amortization of acquired intangible assets		1,028	1,027	1,121	1,168	1,795	1,956	2,012	2,047	4,344	7,810	10,435
Restructuring costs		640				481	130			640	611	7,078
Total operating expenses		66,191	63,013	53,721	67,932	92,840	66,294	62,516	65,013	250,857	286,663	259,477
Income from operations		6,537	6,183	15,482	3,417	(19,042)	3,787	11,336	6,740	31,619	2,821	27,013
Interest and other income, net										(2,331)
Income (loss) before provision for (benefit of) income taxes		5,928	5,280	14,990	3,090	(20,011)	3,028	10,523	6,050	29,288	(410)	23,609
Provision for income taxes		2,000	456	1,896	442	(8,964)	1,487	2,493	2,154	4,794	(2,830)	5,368
Net income		3,928	$ 4,824	$ 13,094	$ 2,648	$ (11,047)	$ 1,541	$ 8,030	$ 3,896	24,494	$ 2,420	$ 18,241
Recurring
Revenues:
Total revenues										473,921
Software, Hardware, and Other Non-recurring
Revenues:
Total revenues										55,252
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		1,220								1,220			2,380
Contract assets		(13,242)								(13,242)			13,446
Income taxes receivable		409								409
Prepaid expenses and other current assets		692								692			(223)
Deferred income taxes, net		4,457								4,457			(2,884)
Contract assets, net of current		(3,747)								(3,747)			2,731
Other assets		(12,611)								(12,611)			6,679
LIABILITIES
Contract liabilities		(1,348)								(1,348)			4,174
Accrued compensation and related benefits		712								712			745
Other current liabilities		(7,838)								(7,838)			9,964
Contract liabilities, net of current		888								888			(1,173)
Shareholders' equity:
Retained earnings		(15,236)								(15,236)			$ 8,419
Revenues:
Total revenues										(1,878)
Total cost of revenue										159
Gross profit										(2,037)
Operating expenses:
Selling, general and administrative										6,762
Total operating expenses										6,762
Income from operations										(8,799)
Income (loss) before provision for (benefit of) income taxes										(8,799)
Provision for income taxes										(1,982)
Net income										(6,817)
Adoption of ASC 606 | ASC 606 Transition Adjustments | Recurring
Revenues:
Total revenues										(430)
Adoption of ASC 606 | ASC 606 Transition Adjustments | Software, Hardware, and Other Non-recurring
Revenues:
Total revenues										(1,448)
Adoption of ASC 606 | Calculated under Revenue Guidance in Effect before Topic 606
ASSETS
Accounts receivable, net		88,679								88,679
Income taxes receivable		4,091								4,091
Prepaid expenses and other current assets		21,518								21,518
Deferred income taxes, net		10,651								10,651
Other assets		19,867								19,867
LIABILITIES
Contract liabilities		54,661								54,661
Accrued compensation and related benefits		26,375								26,375
Other current liabilities		33,226								33,226
Contract liabilities, net of current		888								888
Shareholders' equity:
Retained earnings		$ 96,385								96,385
Revenues:
Total revenues										527,295
Total cost of revenue										246,856
Gross profit										280,439
Operating expenses:
Selling, general and administrative										171,641
Research and development costs, net										80,994
Amortization of acquired intangible assets										4,344
Restructuring costs										640
Total operating expenses										257,619
Income from operations										22,820
Interest and other income, net										(2,331)
Income (loss) before provision for (benefit of) income taxes										20,489
Provision for income taxes										2,812
Net income										17,677
Adoption of ASC 606 | Calculated under Revenue Guidance in Effect before Topic 606 | Recurring
Revenues:
Total revenues										473,491
Adoption of ASC 606 | Calculated under Revenue Guidance in Effect before Topic 606 | Software, Hardware, and Other Non-recurring
Revenues:
Total revenues										$ 53,804

[1] Includes cumulative effect adjustment related to the adoption of ASC 606, as defined in Note 3. See Note 3 for additional details.