Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
Segment reporting information [Line Items]
Net sales	$ 352,134	$ 374,507
Gross Profit	203,079	219,748
Semiconductor products [Member]
Segment reporting information [Line Items]
Net sales	331,852	353,860
Gross Profit	183,633	200,065
Technology licensing [Member]
Segment reporting information [Line Items]
Net sales	20,282	20,647
Gross Profit	$ 19,446	$ 19,683