Consolidated Statements of Comprehensive Earnings (Parenthetical) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 29, 2012	Dec. 31, 2011	Dec. 25, 2010
Unrealized gain (loss) on available-for-sale (AFS) securities, tax effect	$ 12,567	$ 6,324	$ 8,251
Reclassification adjustment for net realized (gain) loss on AFS securities, tax effect	(4,013)	(7,684)	(9,473)
Adjustment to postretirement benefit plan obligation, tax effect	$ (3,498)	$ (3,655)	$ (1,913)