Business and Geographic Segments - Total Assets Held by Business Segments (Detail) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Total assets	$ 2,889.3	$ 2,794.4	$ 2,709.6
Corporate and eliminations
Segment Reporting Information [Line Items]
Total assets	179.3	138.5	104.1
Chemicals | Operating Segment
Segment Reporting Information [Line Items]
Total assets	2,400.7	2,331.8	2,266.6
Component Products | Operating Segment
Segment Reporting Information [Line Items]
Total assets	138.0	132.5	120.4
Real Estate Management And Development | Operating Segment
Segment Reporting Information [Line Items]
Total assets	$ 171.3	$ 191.6	$ 218.5