Changes in accumulated other comprehensive income (loss) (Detail) - USD ($) $ in Thousands		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance		$ (24,161)	$ (8,844)
Other Comprehensive loss		(7,305)	(7,843)
Amounts reclassified from accumulated other comprehensive income	[1]	410	1,422
Ending Balance		(31,056)	(15,265)
Accumulated Translation Adjustment [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance		(6,586)	6,128
Other Comprehensive loss		(7,305)	(7,843)
Amounts reclassified from accumulated other comprehensive income	[1]	0	0
Ending Balance		(13,891)	(1,715)
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	[1]	410	1,422
Ending Balance		$ (17,165)	$ (13,550)

[1] Amount represents amortization of actuarial losses, a component of net periodic benefit cost. This amount was $0.4 million, net of $0.3 million tax benefit, and $1.4 million, net of a $0.9 million tax benefit, for the nine months ended September 30, 2015 and 2014, respectively. For the quarters ended September 30, 2015 and 2014, this amount was $0.1 million, net of $0.1 million tax benefit, and $1.2 million, net of a $0.7 million tax benefit, respectively.