Note Other comprehensive income (loss) (Disclosure of accumulated other comprehensive income (loss)) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Foreign Currency Translation
Beginning Balance	$ (39,956)	$ (35,930)
Other comprehensive loss before reclassifications	139	(705)
Net change	139	(705)
Ending Balance	(39,817)	(36,635)
Adjustment of pension and postretirement benefit plans
Beginning Balance	(211,610)	(211,276)
Amounts reclassified from accumulated other comprehensive income (loss) for amortization of net losses	3,421	3,346
Amounts reclassified from accumulated other comprehensive income (loss) for amortization of prior service credit	(580)	(580)
Net change	2,841	2,766
Ending Balance	(208,769)	(208,510)
Unrealized net holding (losses) gain on investments
Beginning Balance	(68,318)	(9,560)
Other comprehensive (loss) income before reclassification	(2,609)	73,351
Amounts reclassified from accumulated other comprehensive (loss) income	(130)	0
Net change	(2,739)	73,351
Ending Balance	(71,057)	63,791
Unrealized net (losses) gain on cash flow hedges
Beginning Balance	(402)	(120)
Other comprehensive (loss) income before reclassifications	(389)	(1,219)
Amounts reclassified from other accumulated other comprehensive (loss) income	522	943
Net change	133	(276)
Ending Balance	(269)	(396)
Accumulated other comprehensive (loss) income	$ (319,912)	$ (181,750)	$ (320,286)