Significant Accounting Policies Goodwill and Indefinite-Lived Intangible Assets (Details) (USD $)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Goodwill and Intangible Assets Disclosure [Abstract]
Impairment resulting from annual impairment test	$ 0	$ 0	$ 0

Amount of impairment including both the amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized and the impairment loss resulting from write-down of assets, excluding financial assets, lacking physical substance and having a projected indefinite period of benefit to fair value.

No definition available.

Name:	gwr_ImpairmentofGoodwillandIntangibleAssetsIndefinitelived
Namespace Prefix:	gwr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration