Composition of Certain Financial Statement Captions - Summary of Equipment and Improvements (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Mar. 31, 2017
Property Plant And Equipment [Line Items]
Equipment and improvements, gross	$ 68,924	$ 61,899
Accumulated depreciation and amortization	(41,787)	(34,473)
Equipment and improvements, net	27,137	27,426
Computer Equipment [Member]
Property Plant And Equipment [Line Items]
Equipment and improvements, gross	26,886	22,014
Internal-Use Software [Member]
Property Plant And Equipment [Line Items]
Equipment and improvements, gross	14,359	13,053
Furniture and Fixtures [Member]
Property Plant And Equipment [Line Items]
Equipment and improvements, gross	11,448	10,472
Leasehold Improvements [Member]
Property Plant And Equipment [Line Items]
Equipment and improvements, gross	$ 16,231	$ 16,360

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
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-Section S99
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-Subparagraph (SX 210.5-02.14)
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Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Amount after accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business to produce goods and services and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(13))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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-Topic 210
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-Section S99
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-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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-Publisher FASB
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