Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of goodwill arising from a business combination that is expected to be deductible for tax purposes.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The cash outflow associated with the acquisition of a business, net of the cash acquired from the purchase.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3213-108585

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_BusinessAcquisitionAxis=gra_BusinessandAssetsofRiveTechnologyInc.Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=gra_PolyolefinCatalystsBusinessofAlbemarleCorporationMember
Namespace Prefix:
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Balance Type:
Period Type:

Acquisitions - Narrative (Details) - USD ($) $ in Millions	6 Months Ended		12 Months Ended
Acquisitions - Narrative (Details) - USD ($) $ in Millions	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Business Acquisition [Line Items]
Payments to acquire business, net of cash acquired	$ 22.8	$ 420.9
Business and Assets of Rive Technology, Inc. [Member]
Business Acquisition [Line Items]
Payments to acquire business, net of cash acquired	22.8
Polyolefin Catalysts Business Of Albemarle Corporation
Business Acquisition [Line Items]
Payments to acquire business, net of cash acquired			$ 418.0
Goodwill expected to be tax deductible for tax purposes	$ 140.6