Valuation And Qualifying Accounts (Detail) - Allowance for doubtful accounts receivable - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period		$ 4,073	$ 4,975	$ 5,497
Charged to costs and expenses		1,216	180	309
Charged to other accounts		0	0	0
Other	[1]	(520)	(960)	(462)
Balance at end of period		5,339	4,073	4,975
Foreign Currency Translation [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Cumulative translation adjustment		$ 570	$ (122)	$ (369)

[1] Uncollectible accounts written off, net of recoveries.