Expected settlement date of 10-year forward starting interest rate swaps

No definition available.

Name:	gwr_Expectedsettlementdateof10yearforwardstartinginterestrateswaps
Namespace Prefix:	gwr_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Probable future debt

+ References

No definition available.

+ Details

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Namespace Prefix:	gwr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- 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

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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

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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

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

- Details

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

- Definition

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

+ References

No definition available.

+ Details

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

- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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Derivative Financial Instruments Outstanding Interest Rate Swap Agreements (Details) (USD $)	3 Months Ended	0 Months Ended
	Mar. 31, 2015	Sep. 30, 2016
Interest Rate Swap 3 [Member]
Derivative [Line Items]
Effective date	Sep. 30, 2014
Expiration date	Sep. 30, 2015
Interest Rate Swap 3 [Member] \| Notional Period 1 [Member]
Derivative [Line Items]
Notional amount	1,150,000,000
Pay fixed rate, forward interest rate	0.54%
Interest Rate Swap 3 [Member] \| Notional Period 2 [Member]
Derivative [Line Items]
Notional amount	1,100,000,000
Pay fixed rate, forward interest rate	0.54%
Interest Rate Swap 3 [Member] \| Notional Period 3 [Member]
Derivative [Line Items]
Notional amount	1,050,000,000
Pay fixed rate, forward interest rate	0.54%
Interest Rate Swap 3 [Member] \| Notional Period 4 [Member]
Derivative [Line Items]
Notional amount	1,000,000,000
Pay fixed rate, forward interest rate	0.54%
Interest Rate Swap 4 [Member]
Derivative [Line Items]
Effective date	Sep. 30, 2015
Expiration date	Sep. 30, 2016
Interest Rate Swap 4 [Member] \| Notional Period 1 [Member]
Derivative [Line Items]
Notional amount	350,000,000
Pay fixed rate, forward interest rate	0.93%
Interest Rate Swap 5 [Member]
Derivative [Line Items]
Effective date	Sep. 30, 2016
Expiration date	Sep. 30, 2026
Interest Rate Swap 5 [Member] \| Notional Period 1 [Member]
Derivative [Line Items]
Notional amount	100,000,000
Pay fixed rate, forward interest rate	2.79%
Interest Rate Swap 6 [Member]
Derivative [Line Items]
Effective date	Sep. 30, 2016
Expiration date	Sep. 30, 2026
Interest Rate Swap 6 [Member] \| Notional Period 1 [Member]
Derivative [Line Items]
Notional amount	100,000,000
Pay fixed rate, forward interest rate	2.79%
Interest Rate Swap 7 [Member]
Derivative [Line Items]
Effective date	Sep. 30, 2016
Expiration date	Sep. 30, 2026
Interest Rate Swap 7 [Member] \| Notional Period 1 [Member]
Derivative [Line Items]
Notional amount	100,000,000
Pay fixed rate, forward interest rate	2.80%
Scenario, Forecast [Member]
Derivative [Line Items]
Derivative settlement date		Sep. 30, 2016
Variable rate debt [Member] \| Scenario, Forecast [Member]
Derivative [Line Items]
Probable future debt		300,000,000
Fixed rate debt [Member] \| Scenario, Forecast [Member]
Derivative [Line Items]
Probable future debt		300,000,000