Pension and Postretirement Benefits (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Apr. 01, 2012	Mar. 27, 2011
Pension [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 1,198	$ 1,079
Interest cost	5,494	5,223
Expected return on assets	(5,671)	(6,249)
Net amortization and deferrals	1,908	1,295
Net periodic benefit cost	2,929	1,348
Contributions to defined benefit pension plans	2,100
Expected contributions during the remainder of fiscal year	3,700
Postretirement [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	184	171
Interest cost	440	440
Expected return on assets	0	0
Net amortization and deferrals	20	18
Net periodic benefit cost	$ 644	$ 629