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Note E - Acquisition (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2012
Revenue Information On Business Affiliate Prior To Acquisition	$ 10

X

- Definition

No authoritative reference available.

+ References

No definition available.

+ Details

Name:	grc_RevenueInformationOnBusinessAffiliatePriorToAcquisition
Namespace Prefix:	grc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration