Acquisitions - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended			0 Months Ended	3 Months Ended	9 Months Ended		9 Months Ended
	Sep. 28, 2014	Sep. 29, 2013	Sep. 28, 2014	Sep. 29, 2013	Dec. 31, 2013	Feb. 03, 2014 Mayo Healthcare Pty Limited	Sep. 28, 2014 Mayo Healthcare Pty Limited	Sep. 28, 2014 Mayo Healthcare Pty Limited	Feb. 03, 2014 Mayo Healthcare Pty Limited	Sep. 28, 2014 Mayo Healthcare Pty Limited Customer Lists
Business Acquisition [Line Items]
Fair value of the consideration at the date of acquisition					$ 307,000,000				$ 28,500,000
Initial payment						29,000,000
Working capital adjustment related to acquisition						500,000
Transaction expenses								300,000
Net revenues	457,173,000	413,796,000	1,363,824,000	1,245,732,000			6,500,000	19,900,000
Income (loss) from continuing operations before taxes	$ 64,912,000	$ 50,988,000	$ 167,551,000	$ 135,839,000			$ (700,000)	$ 3,100,000
Useful life of intangible assets acquired, years										10 years