Income Taxes (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2012
Income (loss) before income taxes:
Swiss	$ 49,503	$ (53,004)	$ 31,045
Non-Swiss	28,079	(200,324)	93,282
Income (loss) before income taxes	77,582	(253,328)	124,327
Statutory income tax rate (as a percent)	8.50%
Current:
Swiss	127	672	401
Non-Swiss	8,580	(23,146)	24,312
Deferred:
Swiss			(254)
Non-Swiss	(5,429)	(3,336)	(4,369)
Provision for (benefit from) income taxes	3,278	(25,810)	20,090
Reconciliation between provision for (benefit from) income taxes and expected tax provision (benefit) at statutory income tax rate
Expected tax provision (benefit) at statutory income tax rates	6,594	(21,533)	10,568
Income taxes at different rates	497	5,714	2,875
Research and development tax credits	(1,393)	(3,302)	(1,666)
Foreign tax credits		(1,535)
Stock-based compensation	1,608	1,643	2,696
Valuation allowance	182	3,809	(104)
Impairment		18,419
Restructuring charges	1,174	4,336
Tax reserves (releases), net	(4,660)	1,935	6,555
Audit settlement	(400)	(35,608)
Other, net	(324)	312	(834)
Provision for (benefit from) income taxes	3,278	(25,810)	20,090
As Previously Reported
Income (loss) before income taxes:
Swiss		(121,800)	(65,200)
Non-Swiss		(129,300)	157,800
Income (loss) before income taxes		(251,155)	92,590
Deferred:
Provision for (benefit from) income taxes		(25,588)	19,819
Reconciliation between provision for (benefit from) income taxes and expected tax provision (benefit) at statutory income tax rate
Provision for (benefit from) income taxes		(25,588)	19,819
As Previously Reported | Amounts not properly stated
Income (loss) before income taxes:
Swiss		71,000	64,500
Non-Swiss		(71,000)	64,500
Adjustments
Income (loss) before income taxes:
Swiss		(2,200)	31,700
Adjustments | Amounts not properly stated
Income (loss) before income taxes:
Income (loss) before income taxes		$ (2,173)	$ 31,737