Accounts Receivable Grants from Outside Parties (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Receivables [Abstract]
Grant proceeds received from outside parties	$ 28.0	$ 33.9	$ 39.6
Amortization of deferred grants included as offset to depreciation expense	$ 10.4gwr_AmortizationOfDeferredGrants	$ 9.3gwr_AmortizationOfDeferredGrants	$ 8.0gwr_AmortizationOfDeferredGrants

Non-cash offset to depreciation expense from the amortization of grants from outside parties

No definition available.

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