Fair Value Measurements Liabilities Measured on a Recurring Basis - Unobservable Input Reconciliation (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 30, 2013	Mar. 31, 2012
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	$ 1,928	$ 0
Contingent consideration liabilities recorded at fair value at acquisition	0	0
Interest expense charged during the year	42	0
Change in fair value of contingent consideration liabilities	0	0
Settlements	(107)	0
Ending balance	$ 1,863	$ 0