Goodwill and Intangible Assets (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 28, 2013	Dec. 29, 2012	Dec. 31, 2011
Changes in the carrying amount of goodwill
Balance at the beginning of the period, gross	$ 142,658	$ 141,153
Goodwill adjustments related to acquisitions	10,563
Goodwill adjustments related to sale of practice		(29)
Goodwill adjustments related to NeuCo	(63)
Effect of foreign currency translation	308	1,534
Balance at the end of the period, gross	153,466	142,658	141,153
Balance at the beginning of the period, Accumulated impairment losses	(71,893)	(499)
Goodwill impairment	0	(71,394)	0
Balance at the end of the period, Accumulated impairment losses	(71,893)	(71,893)	(499)
Balance at the beginning of the period, net	70,765	140,654
Balance at the end of the period, net	81,573	70,765	140,654
Intangible assets impairment losses	$ 0	$ 0	$ 0