Refers to the total amount of non-cash collateralized letters of credit outstanding

No definition available.

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- References

No definition available.

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- References

No definition available.

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- Definition

Refers to the ratio of secured debt to consolidated EBITDA considered for prepayment of outstanding term loan under restrictive covenant one.

+ References

No definition available.

+ Details

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- Definition

Refers to the ratio of secured debt to consolidated EBITDA considered for prepayment of outstanding term loan under restrictive covenant two.

+ References

No definition available.

+ Details

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- Definition

A measure of a company's ability to pay off its incurred senior secured debt. This ratio gives the investor the approximate amount of time that would be needed to pay off all debt, ignoring the factors of interest, taxes, depreciation and amortization.

+ References

No definition available.

+ Details

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- Definition

Refers to the ratio of consolidated total debt to consolidated EBITDA.

+ References

No definition available.

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- Definition

Term of the interest rate that fluctuates over time as a result of an underlying benchmark interest rate or index.

+ References

No definition available.

+ Details

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- Definition

Refers to decrease in the value of borrowing capacity under the credit facility.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
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- Definition

Refers to the aggregate amount before interest, taxes, depreciation, and amortization ("EBITDA") during the period.

+ References

No definition available.

+ Details

Name:	gdi_EBITDAAmount
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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- References

No definition available.

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- Definition

Refers to expected decrease in value of borrowing capacity under the credit facility next year.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
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- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility under certain restrictive covenants.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
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- Definition

Refers to the maximum amount of non-cash collateralized letters of credit under certain restrictive covenants.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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- Definition

Refers to the percentage of annual excess cash flow used for the prepayment of outstanding term loan.

+ References

No definition available.

+ Details

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- Definition

Refers to the percentage of annual excess cash flow under certain restrictive covenants.

+ References

No definition available.

+ Details

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- Definition

Refers to the percentage of consolidated EBITDA for investments in unrestricted subsidiaries.

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Refers to the percentage of net cash proceeds of all non-ordinary course asset sales considered for prepayment of outstanding term loan.

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Refers to the percentage of net cash proceeds of incurrence of debt considered for prepayment of outstanding term loan.

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Refers to the percentage of original principal amount considered for quarterly installment payment of debt amortization.

+ References

No definition available.

+ Details

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

- Definition

Refers to the percentage of voluntary prepayments net cash proceeds of incurrence of debt considered for prepayment of outstanding term loan.

+ References

No definition available.

+ Details

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

- References

No definition available.

+ Details

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- Definition

Refers to the provision created for non-cash collateralized letters of credit outstanding.

+ References

No definition available.

+ Details

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

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

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

- Definition

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.

+ References

No definition available.

+ Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of unused borrowing capacity under the long-term financing arrangement that is available to the entity as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Balance Type:	credit
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- Definition

Total investments in (A) an entity in which the entity has significant influence, but does not have control, (B) subsidiaries that are not required to be consolidated and are accounted for using the equity and or cost method, and (C) an entity in which the reporting entity shares control of the entity with another party or group. Includes long-term advances receivable from a party that is affiliated with the reporting entity by means of direct or indirect ownership.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.12)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

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

- Definition

The fee, expressed as a percentage of the line of credit facility, for the line of credit facility regardless of whether the facility has been used.

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Debt, Senior Secured Credit Facilities (Details) € in Millions, $ in Millions			3 Months Ended	12 Months Ended
	Aug. 17, 2017 USD ($)	Jun. 30, 2017	Mar. 31, 2018 USD ($)	Dec. 31, 2014	Dec. 31, 2017 USD ($)	Aug. 17, 2017 EUR (€)	Mar. 04, 2016 USD ($)	Jul. 30, 2013 USD ($)	Jul. 30, 2013 EUR (€)
LIBOR [Member]
Interest Rate and Fees [Abstract]
Basis spread on variable rate			1.00%
Term of variable rate			1 month
Federal Funds Effective Rate [Member]
Interest Rate and Fees [Abstract]
Basis spread on variable rate			0.50%
Senior Secured Credit Facility [Member]
Debt Instrument [Line Items]
Aggregate principal amount								$ 2,825.0
Prepayments [Abstract]
Percentage of annual excess cash flow for prepayment of outstanding loan				50.00%
Percentage of annual excess cash flow for prepayment of outstanding loan under restrictive covenants			25.00%
Percentage of the net cash proceeds of all non-ordinary course asset sales for prepayment of outstanding term loan			100.00%
Percentage of net cash proceeds of any incurrence of debt for prepayment of outstanding term loan			100.00%
Certain Covenants and Events of Default [Abstract]
Consolidated Total Debt to Consolidated EBITDA ratio			5.00
Investments in unrestricted subsidiaries			$ 100.0
Percentage of consolidated EBITDA			25.00%
Senior Secured Credit Facility [Member] \| Maximum [Member]
Prepayments [Abstract]
Consolidated secured debt to consolidated EBITDA ratio considered for prepayment of outstanding term loan under covenant one			3.50
Certain Covenants and Events of Default [Abstract]
Letters of credit under restrictive covenant			$ 80.0
Other non-cash collateralized letters of credit maximum amount under restrictive covenant			25.0
Provision of non-cash collateralized letters of credit outstanding			50.0
Aggregate amount of non-cash collateralized letters of credit outstanding			$ 120.0
Senior Secured Credit Facility [Member] \| Minimum [Member]
Prepayments [Abstract]
Consolidated secured debt to consolidated EBITDA ratio considered for prepayment of outstanding term loan under covenant two			3.00
Senior Secured Credit Facility [Member] \| Condition One [Member]
Debt Instrument [Line Items]
EBITDA amount			$ 250.0
Consolidated senior secured debt to consolidated EBITDA ratio			5.50
Senior Secured Credit Facility [Member] \| Condition Two [Member]
Debt Instrument [Line Items]
Consolidated senior secured debt to consolidated EBITDA ratio			4.50
Original Dollar Term Loan Facility [Member]
Debt Instrument [Line Items]
Aggregate principal amount			$ 35.0		$ 50.0			1,900.0
Maximum borrowing capacity	$ 1,285.5
Prepayments [Abstract]
Percentage of premium on prepayment of term loan			1.00%
Amortization and Final Maturity [Abstract]
Percentage of original principal amount for quarterly installment payment of debt amortization			1.00%
Original Dollar Term Loan Facility [Member] \| LIBOR [Member]
Interest Rate and Fees [Abstract]
Basis spread on variable rate	0.00%	1.00%	2.75%
Original Dollar Term Loan Facility [Member] \| Base Rate [Member]
Interest Rate and Fees [Abstract]
Basis spread on variable rate			1.75%
Euro Term Loan Due in 2020 [Member]
Debt Instrument [Line Items]
Aggregate principal amount \| €									€ 400.0
Maximum borrowing capacity \| €						€ 615.0
Prepayments [Abstract]
Percentage of premium on prepayment of term loan			1.00%
Amortization and Final Maturity [Abstract]
Percentage of original principal amount for quarterly installment payment of debt amortization			1.00%
Euro Term Loan Due in 2020 [Member] \| LIBOR [Member]
Interest Rate and Fees [Abstract]
Basis spread on variable rate	0.00%	1.00%	3.00%
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity							$ 360.0	$ 400.0
Decrease in borrowing capacity							$ 40.0
Expected decrease in borrowing capacity next year			$ 269.9
Letters of credit outstanding			7.4
Unused availability			$ 352.6
Consolidated senior secured debt to consolidated EBITDA ratio			7.00
Interest Rate and Fees [Abstract]
Commitment fee			0.50%
Revolving Credit Facility [Member] \| LIBOR [Member]
Interest Rate and Fees [Abstract]
Basis spread on variable rate	0.00%		2.75%
Revolving Credit Facility [Member] \| Base Rate [Member]
Interest Rate and Fees [Abstract]
Basis spread on variable rate			1.75%
Revolving Credit Facility [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Consolidated senior secured debt to consolidated EBITDA ratio			7.50
Certain Covenants and Events of Default [Abstract]
Aggregate amount of non-cash collateralized letters of credit outstanding			$ 300.0
Revolving Credit Facility [Member] \| Condition Three [Member]
Interest Rate and Fees [Abstract]
Commitment fee			0.375%
Revolving Credit Facility [Member] \| Condition Three [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Consolidated senior secured debt to consolidated EBITDA ratio			3.0
Revolving Credit Facility [Member] \| Letter of Credit [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity			$ 200.0