Condensed Consolidated Statements of Comprehensive Income (Loss) (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Jun. 29, 2014	Jun. 30, 2013
Statement Of Income And Comprehensive Income [Abstract]
Net income (loss)	$ 6,000	$ (3,050)
Changes in fair value of marketable securities:
Changes in unrealized gains	199	(1,921)
Net realized losses (gains) reclassified into earnings	63	(394)
Total changes in fair value of marketable securities	262	(2,315)
Foreign currency translation adjustments	58	(294)
Total other comprehensive income (loss)	320	(2,609)
Comprehensive income (loss)	$ 6,320	$ (5,659)