Goodwill - Schedule of Carrying Amount of Goodwill (Detail) $ in Thousands	9 Months Ended
	Sep. 30, 2015 USD ($)
Goodwill [Line Items]
Net goodwill, Beginning balance	$ 931,787
Foreign currency translation	(1,761)
Net goodwill, Ending balance	930,026
Clinical [Member]
Goodwill [Line Items]
Net goodwill, Beginning balance	382,316
Foreign currency translation	(79)
Net goodwill, Ending balance	382,237
Commercial [Member]
Goodwill [Line Items]
Net goodwill, Beginning balance	549,471
Foreign currency translation	(1,682)
Net goodwill, Ending balance	$ 547,789