Revenues Disaggregation of Revenue (Details) $ in Millions	3 Months Ended
	Mar. 31, 2018 USD ($) segment	Mar. 31, 2017 USD ($)
Disaggregation of Revenue [Line Items]
Net sales	$ 431.5	$ 398.0
Number of Reportable Segments | segment	2
Total North America
Disaggregation of Revenue [Line Items]
Net sales	$ 126.0	115.7
Europe Middle East Africa
Disaggregation of Revenue [Line Items]
Net sales	178.7	148.7
Asia Pacific
Disaggregation of Revenue [Line Items]
Net sales	100.2	99.9
Latin America
Disaggregation of Revenue [Line Items]
Net sales	26.6	33.7
Grace Catalysts Technologies [Member]
Disaggregation of Revenue [Line Items]
Net sales	$ 315.8	293.8
Number of Reportable Segments | segment	1
Grace Catalysts Technologies [Member] | Total North America
Disaggregation of Revenue [Line Items]
Net sales	$ 102.1	89.4
Grace Catalysts Technologies [Member] | Europe Middle East Africa
Disaggregation of Revenue [Line Items]
Net sales	119.7	98.3
Grace Catalysts Technologies [Member] | Asia Pacific
Disaggregation of Revenue [Line Items]
Net sales	76.8	80.3
Grace Catalysts Technologies [Member] | Latin America
Disaggregation of Revenue [Line Items]
Net sales	17.2	25.8
Grace Catalysts Technologies [Member] | Refining Catalysts [Member]
Disaggregation of Revenue [Line Items]
Net sales	183.4	178.4
Grace Catalysts Technologies [Member] | Refining Catalysts [Member] | Total North America
Disaggregation of Revenue [Line Items]
Net sales	69.9	61.8
Grace Catalysts Technologies [Member] | Refining Catalysts [Member] | Europe Middle East Africa
Disaggregation of Revenue [Line Items]
Net sales	61.3	54.1
Grace Catalysts Technologies [Member] | Refining Catalysts [Member] | Asia Pacific
Disaggregation of Revenue [Line Items]
Net sales	38.8	41.7
Grace Catalysts Technologies [Member] | Refining Catalysts [Member] | Latin America
Disaggregation of Revenue [Line Items]
Net sales	13.4	20.8
Grace Catalysts Technologies [Member] | Polyolefin and Chemical Catalysts [Member]
Disaggregation of Revenue [Line Items]
Net sales	132.4	115.4
Grace Catalysts Technologies [Member] | Polyolefin and Chemical Catalysts [Member] | Total North America
Disaggregation of Revenue [Line Items]
Net sales	32.2	27.6
Grace Catalysts Technologies [Member] | Polyolefin and Chemical Catalysts [Member] | Europe Middle East Africa
Disaggregation of Revenue [Line Items]
Net sales	58.4	44.2
Grace Catalysts Technologies [Member] | Polyolefin and Chemical Catalysts [Member] | Asia Pacific
Disaggregation of Revenue [Line Items]
Net sales	38.0	38.6
Grace Catalysts Technologies [Member] | Polyolefin and Chemical Catalysts [Member] | Latin America
Disaggregation of Revenue [Line Items]
Net sales	3.8	5.0
Grace Materials Technologies [Member]
Disaggregation of Revenue [Line Items]
Net sales	115.7	104.2	[1]
Grace Materials Technologies [Member] | Total North America
Disaggregation of Revenue [Line Items]
Net sales	23.9	26.3	[1]
Grace Materials Technologies [Member] | Europe Middle East Africa
Disaggregation of Revenue [Line Items]
Net sales	59.0	50.4	[1]
Grace Materials Technologies [Member] | Asia Pacific
Disaggregation of Revenue [Line Items]
Net sales	23.4	19.6	[1]
Grace Materials Technologies [Member] | Latin America
Disaggregation of Revenue [Line Items]
Net sales	9.4	7.9	[1]
Grace Materials Technologies [Member] | Coatings [Member]
Disaggregation of Revenue [Line Items]
Net sales	41.7	35.1
Grace Materials Technologies [Member] | Coatings [Member] | Total North America
Disaggregation of Revenue [Line Items]
Net sales	7.1	7.0
Grace Materials Technologies [Member] | Coatings [Member] | Europe Middle East Africa
Disaggregation of Revenue [Line Items]
Net sales	20.5	16.6
Grace Materials Technologies [Member] | Coatings [Member] | Asia Pacific
Disaggregation of Revenue [Line Items]
Net sales	11.8	9.5
Grace Materials Technologies [Member] | Coatings [Member] | Latin America
Disaggregation of Revenue [Line Items]
Net sales	2.3	2.0
Grace Materials Technologies [Member] | Consumer/Pharma [Member]
Disaggregation of Revenue [Line Items]
Net sales	29.9	30.5
Grace Materials Technologies [Member] | Consumer/Pharma [Member] | Total North America
Disaggregation of Revenue [Line Items]
Net sales	7.7	10.3
Grace Materials Technologies [Member] | Consumer/Pharma [Member] | Europe Middle East Africa
Disaggregation of Revenue [Line Items]
Net sales	13.2	12.2
Grace Materials Technologies [Member] | Consumer/Pharma [Member] | Asia Pacific
Disaggregation of Revenue [Line Items]
Net sales	4.3	3.2
Grace Materials Technologies [Member] | Consumer/Pharma [Member] | Latin America
Disaggregation of Revenue [Line Items]
Net sales	4.7	4.8
Grace Materials Technologies [Member] | Chemical process [Member]
Disaggregation of Revenue [Line Items]
Net sales	37.7	33.9
Grace Materials Technologies [Member] | Chemical process [Member] | Total North America
Disaggregation of Revenue [Line Items]
Net sales	7.4	7.4
Grace Materials Technologies [Member] | Chemical process [Member] | Europe Middle East Africa
Disaggregation of Revenue [Line Items]
Net sales	20.8	18.6
Grace Materials Technologies [Member] | Chemical process [Member] | Asia Pacific
Disaggregation of Revenue [Line Items]
Net sales	7.2	6.8
Grace Materials Technologies [Member] | Chemical process [Member] | Latin America
Disaggregation of Revenue [Line Items]
Net sales	2.3	1.1
Grace Materials Technologies [Member] | Other materials [Member]
Disaggregation of Revenue [Line Items]
Net sales	6.4	4.7
Grace Materials Technologies [Member] | Other materials [Member] | Total North America
Disaggregation of Revenue [Line Items]
Net sales	1.7	1.6
Grace Materials Technologies [Member] | Other materials [Member] | Europe Middle East Africa
Disaggregation of Revenue [Line Items]
Net sales	4.5	3.0
Grace Materials Technologies [Member] | Other materials [Member] | Asia Pacific
Disaggregation of Revenue [Line Items]
Net sales	0.1	0.1
Grace Materials Technologies [Member] | Other materials [Member] | Latin America
Disaggregation of Revenue [Line Items]
Net sales	$ 0.1	$ 0.0

[1] (1)Under the modified retrospective method, prior-period information has not been adjusted and continues to be reported in accordance with Grace’s historical accounting under ASC 605.