Goodwill and Other Intangible Assets (Gross Carrying Amount and Accumulated Amortization of Goodwill) (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 28, 2013	Sep. 28, 2013	Jan. 04, 2013	Dec. 29, 2012
Changes in gross carrying amount and accumulated amortization of goodwill
Gross carrying amount, balance at the beginning of the period	$ 1,213,609	$ 1,234,271
Gross carrying amount, acquired during the period	19,273
Gross carrying amount, foreign exchange/impairment	1,389
Accumulated impairment loss, balance at the beginning of the period	(1,005,000)	(1,005,000)
Goodwill	229,271		19,096	208,609
Research Models and Services [Member]
Changes in gross carrying amount and accumulated amortization of goodwill
Gross carrying amount, balance at the beginning of the period	63,139	82,773
Gross carrying amount, acquired during the period	19,273
Gross carrying amount, foreign exchange/impairment	361
Preclinical Services [Member]
Changes in gross carrying amount and accumulated amortization of goodwill
Gross carrying amount, balance at the beginning of the period	1,150,470	1,151,498
Gross carrying amount, acquired during the period	0
Gross carrying amount, foreign exchange/impairment	1,028
Accumulated impairment loss, balance at the beginning of the period	$ (1,005,000)	$ (1,005,000)