Certain Financial Statement Information - Schedule of Property and equipment (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended			3 Months Ended						12 Months Ended						12 Months Ended	1 Months Ended	12 Months Ended	1 Months Ended			12 Months Ended						1 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2012	Jun. 30, 2013 Minimum	Jun. 30, 2013 Maximum	Mar. 31, 2014 Machinery and Equipment		Mar. 31, 2013 Machinery and Equipment		Mar. 31, 2014 Machinery and Equipment Minimum		Mar. 31, 2014 Machinery and Equipment Maximum		Mar. 31, 2014 Leasehold Improvements	Mar. 31, 2013 Leasehold Improvements	Mar. 31, 2014 Leasehold Improvements Minimum	Mar. 31, 2014 Leasehold Improvements Minimum California	Mar. 31, 2014 Leasehold Improvements Maximum	Mar. 31, 2014 Leasehold Improvements Maximum California	Mar. 31, 2014 Computers, Office Furniture and Equipment	Mar. 31, 2013 Computers, Office Furniture and Equipment	Mar. 31, 2014 Computers, Office Furniture and Equipment Minimum	Mar. 31, 2014 Computers, Office Furniture and Equipment Maximum	Mar. 31, 2014 Buildings		Mar. 31, 2013 Buildings		Mar. 31, 2014 Buildings California	Mar. 31, 2014 Land		Mar. 31, 2013 Land
Property, Plant and Equipment [Line Items]
Useful life				1 year	7 years					5 years	[1]	7 years	[1]			1 year	5 years	5 years	15 years			3 years	7 years	0 years				31 years 6 months
Schedule of Property and equipment
Property and equipment, gross	$ 99,442	$ 110,306				$ 44,503	[1]	$ 40,063	[1]					$ 11,574	$ 14,202					$ 43,365	$ 43,485			$ 0	[2]	$ 2,756	[2]		$ 0	[2]	$ 9,800	[2]
Less: accumulated depreciation and amortization	(78,696)	(75,915)
Property and equipment, net	20,746	34,391																										14,300
Proceeds from sale of buildings	40,176	0	0																									40,800
NBV of building sold	20,746	34,391																										14,300
Gain on sale of building	$ (25,815)	$ 0	$ 0																									$ (25,800)

[1] Includes capitalized mask costs

[2] In March, 2014, The Company sold its headquarters building and related parcel of land in Sunnyvale, California for a purchase price of $40.8 million in cash. The building was being depreciated over the useful life of 31.5 years and the leasehold improvements associated with the building were being depreciated over the useful life of 5 to 15 years. The net book value of the properties sold was approximately $14.3 million on the closing date and the Company recorded a gain of $25.8 million in the fiscal year ended March 31, 2014. The Company leases a portion of the space on a lease which expires in August, 2015.