CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 28, 2015	Jun. 29, 2014	Jun. 28, 2015	Jun. 29, 2014
Statement of Comprehensive Income [Abstract]
Gain (loss) associated with available-for-sale securities, tax benefit (expense)	$ 1	$ (3)	$ 13	$ (20)
Gain (loss) associated with pension and other postretirement benefits, tax benefit (expense)	$ (5,331)	$ 2,200	$ (4,077)	$ 5,709