Inventories, Net (Tables)

12 Months Ended

Dec. 31, 2018

Inventory Disclosure [Abstract]

Inventories, Net

	December 31,
	2017		2018
	(In millions)
Raw materials:
Chemicals	$	106.9	$	93.1
Component products		2.7		2.7
Total raw materials		109.6		95.8
Work in process:
Chemicals		20.8		23.5
Component products		9.8		11.1
Total in-process products		30.6		34.6
Finished products:
Chemicals		192.2		317.6
Component products		2.8		3.3
Total finished products		195.0		320.9
Supplies (chemicals)		63.2		64.5
Total	$	398.4	$	515.8