Goodwill (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2016		Dec. 31, 2015
Goodwill [Line Items]
Opening balance	$ 588,434	[1]	$ 463,324
Current period acquisitions (Note 3)			133,123
Prior period acquisitions (Note 3)	5,773		4,418
Foreign exchange movement	(322)		(12,431)
Closing balance	$ 593,885		$ 588,434	[1]

[1] The December 31, 2015 Balance Sheet has been retrospectively restated as required to reflect the requirements of new guidance in respect of the presentation of debt issue costs.