Changes In Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance	$ 245,225	$ 212,599	$ 200,087
Ending Balance	273,456	245,225	212,599
Foreign Currency Translation Adjustment
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance	(16,920)	(6,586)	6,128
Other Comprehensive loss	(10,965)	(10,334)	(12,714)
Amounts reclassified from accumulated other comprehensive loss		0	0
Ending Balance	(27,885)	(16,920)	(6,586)
Defined Benefit Pension Adjustment
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance	(17,665)	(17,575)	(14,972)
Other Comprehensive loss	(2,969)	(637)	(6,099)
Amounts reclassified from accumulated other comprehensive loss	569	547	3,496
Ending Balance	(20,065)	(17,665)	(17,575)
Total Accumulated Other Comprehensive (Loss) Income
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance	(34,585)	(24,161)	(8,844)
Other Comprehensive loss	(13,934)	(10,971)	(18,813)
Amounts reclassified from accumulated other comprehensive loss	569	547	3,496
Ending Balance	$ (47,950)	$ (34,585)	$ (24,161)