Quarterly Financial Summary (Unaudited) (Footnote) (Detail) - USD ($) $ in Thousands	3 Months Ended				12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Gain (loss) on sales of businesses, net	$ 0	$ 0	$ 974	$ 121,324	$ 0	$ 122,298	$ 0
Metal Sulfides Business
Gain (loss) on sales of businesses, net						11,500
Mineral Flame Retardants and Specialty Chemicals Businesses
Gain (loss) on sales of businesses, net						112,300
Chemetall Surface Treatment
Gain (loss) on sales of businesses, net					$ 257,000
Discrete non-cash charge			$ 416,700
Gain on sale of business, net of tax	$ 135,000
Corporate | Wafer Reclaim
Gain (loss) on sales of businesses, net						$ (1,500)