CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Apr. 01, 2012
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 18,432	$ 75,197
Other comprehensive income before tax:
Foreign currency translation adjustments	(342)	1,447
Available-for-sale securities:
Unrealized gain on investments	1,980	338
Reclassification of net realized loss/(gain) on investments to net income	17	(142)
Derivative financial instruments:
Unrealized (loss)/gain on derivatives	(32)	640
Reclassification of net realized (gain)/loss on derivatives to net income	(162)	673
Amortization of transition asset, prior service cost and net actuarial loss on defined benefit pension and post-retirement plans	5,044	3,969
Other comprehensive income before tax	6,505	6,925
Income tax expense on unrealized gain on investments	740
Other comprehensive income, net of tax	5,765	6,925
Comprehensive income	$ 24,197	$ 82,122