Noncontrolling Interests in Consolidated Affiliates (Tables)	9 Months Ended
Sep. 30, 2012
Noncontrolling Interests in Consolidated Affiliates
Schedule of condensed statements of operations for consolidated affiliates for which there is a noncontrolling interest	Table 1
Schedule of condensed balance sheets for consolidated affiliates for which there is a noncontrolling interest	Table 2

Tabular disclosure of statements of operations of joint ventures with unaffiliated third parties for which there is a noncontrolling interest, included in consolidated financial statements.

No definition available.

Name:	gra_ScheduleOfCondensedStatementsOfOperationsOfJointVenturesWithUnaffiliatedThirdPartiesTableTextBlock
Namespace Prefix:	gra_
Data Type:	nonnum:textBlockItemType
Balance Type:	na
Period Type:	duration