Certain Financial Statement Information - Realized Gain on Short-Term Investments and Interest Income, Net (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Schedule of Interest Income, Net
Net realized gain on short-term investments	$ 34	$ 127	$ 66	$ 1,557
Interest income, net	208	130	406	319
Realized gain on short-term investments and interest income, net	$ 242	$ 257	$ 472	$ 1,876