Certain Financial Statement Information - Schedule of Interest income (expense), net and other-than-temporary impairment (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended															12 Months Ended
	Mar. 31, 2015		Dec. 31, 2014	Sep. 30, 2014		Jun. 30, 2014		Mar. 31, 2014		Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Schedule of Interest Income, Net
Net realized gain on short-term investments																$ 1,353	$ 3,360	$ 1,391
Interest income, net																1,411	1,692	2,347
Impairments of short-term investments and marketable securities	(500)			(2,500)												0	0	(1,143)
Interest income, net	$ 1,030	[1]	$ 475	$ (2,112)	[2]	$ 315	[3]	$ 418	[4]	$ 617	[5]	$ 576	[6]	$ 3,795	[7]	$ 2,764	$ 5,052	$ 2,595

[1] The consolidated operating results for the fourth quarter of fiscal 2015 included a charge of $2.1 million related to the Veloce consideration, a charge of $4.1 million related to restructuring and an impairment charge of $0.5 million related to a strategic investment.

[2] The consolidated operating results for the second quarter of fiscal 2015 included an impairment charge of $2.5 million related to a strategic investment.

[3] The consolidated operating results for the first quarter of fiscal 2015 included a charge of $7.1 million related to the Veloce consideration and a charge of $1.2 million related to restructuring.

[4] The consolidated operating results for the fourth quarter of fiscal 2014 included a gain on sale of building of $25.8 million.

[5] The consolidated operating results for the third quarter of fiscal 2014 included a charge of $2.9 million related to the Veloce consideration.

[6] The consolidated operating results for the second quarter of fiscal 2014 included a charge of $30.4 million related to the Veloce consideration and a charge of $1.0 million related to restructuring.

[7] The consolidated operating results for the first quarter of fiscal 2014 included a charge of $9.3 million related to the Veloce consideration and a gain on sale of TPack of $19.7 million.