Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Segment reporting information [Line Items]
Net sales	$ 546,243	$ 492,669	$ 1,075,119	$ 955,461
Gross Profit	307,454	288,863	613,973	555,437
Semiconductor products [Member]
Segment reporting information [Line Items]
Net sales	523,659	467,843	1,032,098	908,117
Gross Profit	284,870	264,037	570,952	508,093
Technology licensing [Member]
Segment reporting information [Line Items]
Net sales	22,584	24,826	43,021	47,344
Gross Profit	$ 22,584	$ 24,826	$ 43,021	$ 47,344