Derivative Financial Instruments Settled Interest Rate Swap Agreements (Details) $ in Thousands	9 Months Ended
Sep. 30, 2018 USD ($)
Interest Rate Swap 1 [Member]
Derivatives, Fair Value [Line Items]
Effective Date	Sep. 30, 2016
Settlement Date	Aug. 15, 2018
Maturity Date	Sep. 30, 2026
Notional Amount	$ 100,000
Pay Fixed Rate	2.76%
Interest Rate Swap 2 [Member]
Derivatives, Fair Value [Line Items]
Effective Date	Sep. 30, 2016
Settlement Date	Aug. 15, 2018
Maturity Date	Sep. 30, 2026
Notional Amount	$ 100,000
Pay Fixed Rate	2.74%
Interest Rate Swap 3 [Member]
Derivatives, Fair Value [Line Items]
Effective Date	Sep. 30, 2016
Settlement Date	Aug. 15, 2018
Maturity Date	Sep. 30, 2026
Notional Amount	$ 100,000
Pay Fixed Rate	2.73%

Derivative, Settlement Date

No definition available.

Name:	gwr_DerivativeSettlementDate
Namespace Prefix:	gwr_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 13
-Sentence Column B

+ Details

Name:	invest_DerivativeNotionalAmount
Namespace Prefix:	invest_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

- Definition

Stated rate on an interest rate forward or futures contract.

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativeForwardInterestRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Date the entity entered into the derivative contract, in CCYY-MM-DD format.

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativeInceptionDates
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Date the derivative contract matures, in CCYY-MM-DD format.

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativeMaturityDates
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- 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

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

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=gwr_InterestRateSwap1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=gwr_InterestRateSwap2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=gwr_InterestRateSwap3Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: