Stock-Based Compensation - Stock Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Stock Based Compensation [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost	$ 6,689	$ 5,939	$ 14,863	$ 12,043
Summary of Stock-Based Compensation Expense of Stock Options and Restricted Stock Units
Stock-based compensation capitalized to inventory	7	(5)	(2)	(17)
Allocated Share-based Compensation Expense	6,696	5,934	14,861	12,026
Cost of Revenues
Stock Based Compensation [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost	165	121	332	226
Research and Development Expense
Stock Based Compensation [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost	4,530	3,955	10,523	8,015
Selling, General and Administrative
Stock Based Compensation [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost	1,994	1,863	4,008	3,802
Employee Stock [Member]
Stock Based Compensation [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost	315	289	642	496
Outstanding RSUs
Stock Based Compensation [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost	$ 6,374	$ 5,650	$ 14,221	$ 11,547

Stock based compensation expenses related to stock options and restricted stock units.

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- Definition

Stock-based compensation.

+ References

No definition available.

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- Definition

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 14.F)
-URI http://asc.fasb.org/extlink&oid=27013229&loc=d3e301413-122809

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
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-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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Represents the compensation cost capitalized during the period arising from equity-based compensation arrangements (for example, shares of stock, units, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(1)(ii)
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Amount of capitalized and expensed compensation cost from equity-based compensation arrangements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
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