Other Comprehensive Income (Loss) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 29, 2012	Oct. 01, 2011	Sep. 29, 2012	Oct. 01, 2011
Unrealized gain (loss) on interest rate swaps:
Before income taxes	$ (230)	$ (282)	$ (748)	$ (495)
Income taxes	(88)	(107)	(283)	(188)
Net of taxes	(142)	(175)	(465)	(307)
Reclassification of loss into earnings from interest rate swaps:
Before income taxes	37	137	114	415
Income taxes	14	52	43	158
Net of taxes	23	85	71	257
Amortization of unrealized loss on dedesignated interest rate swaps:
Before income taxes	118	21	353	21
Income taxes	45	8	134	8
Net of taxes	73	13	219	13
Reclassification of net actuarial gain into earnings from postretirement benefit plans:
Before income taxes	(10)	(7)	(29)	(21)
Income taxes	(4)	(3)	(12)	(8)
Net of taxes	(6)	(4)	(17)	(13)
Reclassification of prior service credits into earnings from postretirement benefit plans:
Before income taxes	(22)	(22)	(66)	(67)
Income taxes	(8)	(8)	(26)	(26)
Net of taxes	(14)	(14)	(40)	(41)
Other comprehensive income (loss)	$ (66)	$ (95)	$ (232)	$ (91)