Changes In Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014		Dec. 31, 2013
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance		$ 212,599	$ 200,087		$ 174,496
Ending Balance		245,225	212,599		200,087
Foreign Currency Translation Adjustment
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance		(6,586)	6,128		3,178
Other comprehensive income (loss)		$ (10,334)	(12,714)		2,950
Amounts reclassified from accumulated other comprehensive loss			0		0
Ending Balance		$ (16,920)	(6,586)		6,128
Defined Benefit Pension Adjustment
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance		(17,575)	(14,972)	[1]	(21,544)
Other comprehensive income (loss)		(637)	(6,099)		5,909
Amounts reclassified from accumulated other comprehensive loss	[1]	547	3,496		663
Ending Balance		(17,665)	(17,575)		(14,972)	[1]
Total Accumulated Other Comprehensive (Loss) Income
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance		(24,161)	(8,844)		(18,366)
Other comprehensive income (loss)		(10,971)	(18,813)		8,859
Amounts reclassified from accumulated other comprehensive loss		547	3,496		663
Ending Balance		$ (34,585)	$ (24,161)		$ (8,844)

[1] (b) Amount represents the amortization of actuarial losses to pension expense arising from the Company’s postretirement benefit obligation. This amount was $0.5 million, net of $0.3 million tax benefit in 2015, $3.5 million, net of $2.1 million tax benefit, which included $3.0 million, net of $1.9 million tax benefit for pension settlement costs in 2014, and $0.7 million, net of $0.4 million tax benefit in 2013. (See Note 8)