Schedule of Inventories Net (Detail) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016
Inventory Disclosure [Abstract]
Finished products	$ 495,793	$ 479,291	$ 443,470
Products in process and raw materials	61,815	61,171	59,761
Supplies and expendable parts	120,054	116,024	112,022
Inventories, Gross	677,662	656,486	615,253
Less: Allowances	(140,662)	(134,862)	(129,886)
Total	$ 537,000	$ 521,624	$ 485,367