Employee Benefit Programs Employee Bonus Programs (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Employee Benefits and Share-based Compensation [Abstract]
Amounts Awarded Under Performance-Based Bonus Programs	$ 15.8	$ 17.7	$ 14.2

Amounts Awarded Under Performance-Based Bonus Programs during the period

No definition available.

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