Changes in accumulated other comprehensive income (loss) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	$ (24,161)		$ (8,844)
Other Comprehensive loss	(9,919)		(336)
Amounts reclassified from accumulated other comprehensive income	137	[1]	111	[1]
Ending Balance	(33,943)		(9,069)
Accumulated Translation Adjustment [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	(6,586)		6,128
Other Comprehensive loss	(9,919)		(336)
Amounts reclassified from accumulated other comprehensive income	0		0
Ending Balance	(16,505)		5,792
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	(17,575)		(14,972)
Other Comprehensive loss	0		0
Amounts reclassified from accumulated other comprehensive income	137	[1]	111	[1]
Ending Balance	$ (17,438)		$ (14,861)

[1] Amount represents amortization of actuarial losses, a component of net periodic benefit cost. This amount was $0.1 million net of $0.1 million tax benefit for the quarters ended March 31, 2015 and 2014, respectively.