Refers to the annual percentage increase in fee.

No definition available.

Name:	gdi_AnnualPercentageIncreaseInFee
Namespace Prefix:	gdi_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Refers to the monitoring agreement termination fee associated with related party.

+ References

No definition available.

+ Details

Name:	gdi_MonitoringAgreementTerminationFee
Namespace Prefix:	gdi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Carrying amount as of the balance sheet date of obligations due all related parties. For classified balance sheets, represents the current portion of such liabilities (due within one year or within the normal operating cycle if longer).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(k)(1))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(a))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_DueToRelatedPartiesCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of transactions with related party during the financial reporting period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39622-107864

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39603-107864

+ Details

Name:	us-gaap_RelatedPartyTransactionAmountsOfTransaction
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- References

No definition available.

+ Details

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

- Definition

Expenses recognized resulting from transactions (excluding transactions that are eliminated in consolidated or combined financial statements) with related party.

+ References

+ Details

Name:	us-gaap_RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=gdi_KohlbergKravisAndRobertsCoLPMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=gdi_LenderMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=gdi_EuroTermLoanFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=gdi_UnderwriterDiscountsAndCommissionsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=gdi_ServicesRenderedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=gdi_MonitoringAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=gdi_ManagementFeesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=gdi_OutOfPocketExpensesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Related Party (Details) - KKR [Member] € in Millions, $ in Millions		1 Months Ended	12 Months Ended
	May 31, 2018 USD ($)	Aug. 31, 2017 USD ($)	Dec. 31, 2018 EUR (€)	Dec. 31, 2017 USD ($)	Dec. 31, 2017 EUR (€)	Dec. 31, 2016 USD ($)	Dec. 31, 2018 USD ($)
Lender in Senior Secured Credit Facilities [Member] \| Euro Term Loan Facility [Member]
Related Party Transaction, Due to Related Party [Abstract]
Related party transaction amount \| €			€ 33.5		€ 49.9
Underwriter Discounts and Commissions [Member]
Related Party Transaction, Due to Related Party [Abstract]
Related party transaction amount	$ 5.2			$ 8.9
Services Rendered for Debt Refinancing Transaction [Member]
Related Party Transaction, Due to Related Party [Abstract]
Related party transaction amount		$ 1.5
Monitoring Agreement [Member]
Related Party Transaction, Due to Related Party [Abstract]
Annual management fee due to related party							$ 3.5
Monitoring agreement termination fee				16.2
Annual percentage increase in fee			5.00%
Management Fees [Member]
Related Party Transaction, Due to Related Party [Abstract]
Expenses with related party				$ 1.1		$ 4.1
Out-of-Pocket Expenses [Member]
Related Party Transaction, Due to Related Party [Abstract]
Expenses with related party						$ 0.7