CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE EARNINGS (Parenthetical) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 27, 2014	Sep. 28, 2013	Sep. 27, 2014	Sep. 28, 2013
Statement of Comprehensive Income [Abstract]
Unrealized (loss) gain on available-for-sale (AFS) securities, tax effect	$ (8,205)	$ 20,187	$ 23,437	$ 19,711
Reclassification adjustment for net realized gain on AFS securities, tax effect	(4,998)	(1,756)	(13,026)	(5,330)
Adjustment to postretirement benefit plan obligation, tax effect	$ 54	$ 508	$ 160	$ 1,524