Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	$ (89,633)	$ (85,803)
Other comprehensive income before reclassifications	3,291	3,102
Amounts reclassified from accumulated other comprehensive income	(1,647)	(1,464)
Net current-period other comprehensive income	1,644	1,638
Ending Balance	(87,989)	(84,165)
Pension and Other Postretirement Benefits Items
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	(84,852)	(83,279)
Other comprehensive income before reclassifications	3,291	2,949
Amounts reclassified from accumulated other comprehensive income	(1,647)	(1,464)
Net current-period other comprehensive income	1,644	1,485
Ending Balance	(83,208)	(81,794)
Foreign Currency Items
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	(4,781)	(2,524)
Other comprehensive income before reclassifications	0	153
Amounts reclassified from accumulated other comprehensive income	0	0
Net current-period other comprehensive income	0	153
Ending Balance	$ (4,781)	$ (2,371)