Certain Financial Statement Information (Details 3) (USD $) In Thousands, unless otherwise specified					6 Months Ended
	Sep. 30, 2013		Mar. 31, 2013		Sep. 30, 2013 Machinery and Equipment [Member] Minimum [Member]	Sep. 30, 2013 Machinery and Equipment [Member] Maximum [Member]	Sep. 30, 2013 Leasehold Improvements [Member] Minimum [Member]	Sep. 30, 2013 Leasehold Improvements [Member] Maximum [Member]	Sep. 30, 2013 Computers, Office Furniture and Equipment [Member] Minimum [Member]	Sep. 30, 2013 Computers, Office Furniture and Equipment [Member] Maximum [Member]	Sep. 30, 2013 Buildings [Member]
Schedule of Property and equipment
Useful life					5 years	7 years	1 year	15 years	3 years	7 years	31 years 6 months
Machinery and equipment	$ 44,900	[1]	$ 40,063	[1]
Leasehold improvements	11,480		14,202
Computers, office furniture and equipment	43,845		43,485
Buildings	2,756		2,756
Land	9,800		9,800
Property and equipment, gross	112,781		110,306
Less: accumulated depreciation and amortization	(78,789)		(75,915)
Property and equipment, net	$ 33,992		$ 34,391	[2]

[1] Includes capitalized mask costs.

[2] Amounts have been derived from the March 31, 2013 audited consolidated financial statements.