Goodwill - Schedule of Carrying Amount of Goodwill (Detail) $ in Thousands	6 Months Ended
	Jun. 30, 2015 USD ($)
Goodwill [Line Items]
Net goodwill, Beginning balance	$ 931,787
Foreign currency translation	(1,213)
Net goodwill, Ending balance	930,574
Clinical [Member]
Goodwill [Line Items]
Net goodwill, Beginning balance	382,316
Foreign currency translation	(18)
Net goodwill, Ending balance	382,298
Commercial [Member]
Goodwill [Line Items]
Net goodwill, Beginning balance	549,471
Foreign currency translation	(1,195)
Net goodwill, Ending balance	$ 548,276