Composition of Certain Financial Statement Captions - Summary of Equipment and Improvements (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Mar. 31, 2018
Property Plant And Equipment [Line Items]
Equipment and improvements, gross	$ 72,032	$ 70,599
Accumulated depreciation and amortization	(48,863)	(43,804)
Equipment and improvements, net	23,169	26,795
Computer Equipment
Property Plant And Equipment [Line Items]
Equipment and improvements, gross	28,205	27,347
Internal-Use Software
Property Plant And Equipment [Line Items]
Equipment and improvements, gross	17,136	15,804
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Equipment and improvements, gross	10,966	11,432
Leasehold Improvements
Property Plant And Equipment [Line Items]
Equipment and improvements, gross	$ 15,725	$ 16,016

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

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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.

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