- Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at January 1,	$ 25,001	$ 22,509
Gross increases for tax positions of prior years	1,935	3,065
Gross increases for tax positions of current year	2,397	4,672
Decreases due to settlements and other prior year tax positions	(10,338)	(3,424)
Decreases for lapse of statute of limitations	0	(1,782)
Currency translation effect on foreign balances	101
Currency translation effect on foreign balances		(39)
Balance at December 31,	19,096	25,001
Reserves related to potential interest at December 31,	1,018	1,389
Unrecognized tax benefits at December 31,	$ 20,114	$ 26,390