XML 41 R31.htm IDEA: XBRL DOCUMENT v3.21.1

Note 7 - Pension and Other Postretirement Benefits (Details Textual) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Defined Benefit Plan Effect On Pension Expense	$ 0	$ 1,500

X

- Definition

Defined benefit plan effect on pension expense.

+ References

No definition available.

+ Details

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