Reserve for Doubtful Receivables (Detail) - USD ($) $ in Thousands	6 Months Ended			12 Months Ended
	Jun. 30, 2017	Jun. 30, 2016		Dec. 31, 2016
Receivables [Abstract]
Opening balance	$ 15,519	$ 11,530		$ 11,530
Additions due to acquisitions	235
Additions charged to cost and expense	1,793	$ 4,467	[1]	7,282
Deductions/effect of exchange rate fluctuations	20			(3,293)
Closing balance	$ 17,567			$ 15,519

[1] Income taxes, net income and cash flows for the six months ended June 30, 2016, have been restated due to the adoption of ASU No. 2016-09 in 2016 with effect from January 1, 2016.