Changes in Operations Freightliner Pro Forma (Details) (USD $)	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014	Mar. 25, 2015
Foreign currency exchange rate	1.51	1.66	1.49
Freightliner [Member]
Operating revenues	$ 553,649,000	$ 576,060,000
Net income	47,789,000	24,981,000
Basic earnings per common share	$ 0.86	$ 0.46
Diluted earnings per common share	$ 0.84	$ 0.44
Pro Forma [Member] \| Acquisition-related costs [Member] \| Freightliner [Member]
Net income	9,500,000	(9,500,000)
Pro forma net income (loss) before tax	12,600,000	(12,600,000)
Pro Forma [Member] \| Loss on settlement of foreign currency forward purchase contracts \| Freightliner [Member]
Net income	11,600,000
Pro forma net income (loss) before tax	18,700,000
Freightliner [Member] \| Pro Forma [Member] \| Acquisition-related costs [Member]
Net income	9,100,000	(11,900,000)
Pro forma net income (loss) before tax	$ 12,200,000	$ (15,900,000)

Business Acquisition, Pro Forma Net Income (Loss) Before Tax

No definition available.

Name:	gwr_BusinessAcquisitionProFormaNetIncomeLossBeforeTax
Namespace Prefix:	gwr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The pro forma basic net income per share for a period as if the business combination or combinations had been completed at the beginning of a period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (h)(2)-(3)

-URI http://asc.fasb.org/extlink&oid=56956515&loc=d3e1392-128463

+ Details

Name:	us-gaap_BusinessAcquisitionProFormaEarningsPerShareBasic
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

The pro forma diluted net income per share for a period as if the business combination or combinations had been completed at the beginning of a period.

+ References

+ Details

Name:	us-gaap_BusinessAcquisitionProFormaEarningsPerShareDiluted
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

The pro forma net Income or Loss for the period as if the business combination or combinations had been completed at the beginning of a period.

+ References

+ Details

Name:	us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The pro forma revenue for a period as if the business combination or combinations had been completed at the beginning of the period.

+ References

+ Details

Name:	us-gaap_BusinessAcquisitionsProFormaRevenue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Foreign exchange rate used to translate amounts denominated in functional currency to reporting currency.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 830

-SubTopic 30

-Section S99

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6897108&loc=SL6897125-166521

+ Details

Name:	us-gaap_ForeignCurrencyExchangeRateTranslation1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	dei_LegalEntityAxis=gwr_FreightlinerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=gwr_FreightlinerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementScenarioAxis=us-gaap_ProFormaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: