Goodwill - Schedule of Carrying Amount of Goodwill (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2016 USD ($)
Goodwill [Line Items]
Net goodwill, Beginning balance	$ 895,369
Foreign currency translation	1,396
Net goodwill, Ending balance	896,765
Clinical [Member]
Goodwill [Line Items]
Net goodwill, Beginning balance	382,215
Foreign currency translation	(1)
Net goodwill, Ending balance	382,214
Commercial [Member]
Goodwill [Line Items]
Net goodwill, Beginning balance	513,154
Foreign currency translation	1,397
Net goodwill, Ending balance	$ 514,551