CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE EARNINGS (Parenthetical) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 25, 2011	Jun. 30, 2012	Jun. 25, 2011
Unrealized gain on available-for-sale (AFS) securities, tax effect	$ (7,884)	$ 7,438	$ 5,193	$ 13,723
Reclassification adjustment for net realized gain on AFS securities, tax effect	(1,609)	(4,840)	(1,701)	(7,944)
Adjustment to postretirement benefit plan obligation, tax effect	$ 301	$ 104	$ 602	$ 207