Certain Financial Statement Information - Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax, Portion Attributable to Parent		$ 26	$ (233)	$ (119)	$ (370)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	[1]			115,038
Net current-period other comprehensive income (loss), net of tax		(4)	(429)	(2)	(2,219)
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax, Portion Attributable to Parent	[2]	(30)	$ (196)	117	$ (1,849)
Ending Balance		112,958		112,958
Foreign currency translation adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax				(119)
Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent				0
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance				(2,486)
Ending Balance		(2,605)		(2,605)
Unrealized gain (loss) on short-term investments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax				167
Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent				(50)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance				(7,067)
Ending Balance		(6,950)		(6,950)
Total
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax				48
Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent				(50)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance				(9,553)
Net current-period other comprehensive income (loss), net of tax				(2)
Ending Balance		$ (9,555)		$ (9,555)

[1] The Condensed Consolidated Balance Sheet as of March 31, 2016 has been derived from the audited Consolidated Financial Statements at that date but does not include all disclosures required by generally accepted accounting principles for complete financial statements.

[2] The amounts reclassified from accumulated other comprehensive loss and recorded in realized gain on short-term investments and interest income, net in the Condensed Consolidated Statement of Operations related to the sale of short-term investments were $22,000 and $137,000 for the three months ended September 30, 2016 and 2015, respectively, and $50,000 and $1,498,000 for the six months ended September 30, 2016 and 2015, respectively. Refer to Note 2, Certain Financial Statement Information, to the Condensed Consolidated Financial Statements for additional details.