Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2020	Apr. 30, 2020
Document and Entity Information
Title of 12(b) Security	Common Stock, $0.01 par value per share
Entity Incorporation, State or Country Code	DE
Trading Symbol	GRA
Entity Registrant Name	W. R. GRACE & CO.
Entity Address, Address Line One	7500 Grace Drive
Entity Address, City or Town	Columbia
Entity Address, State or Province	MD
Entity Address, Postal Zip Code	21044-4098
City Area Code	(410)
Local Phone Number	531-4000
Entity Central Index Key	0001045309
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2020
Document Transition Report	false
Entity File Number	1-13953
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		66,172,136
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q1
Entity Tax Identification Number	65-0773649
Security Exchange Name	NYSE