Other Employee Benefit Programs Employee Bonus Programs (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Employee Benefits and Share-based Compensation, Noncash [Abstract]
Amounts Awarded Under Performance-Based Bonus Programs	$ 20	$ 23	$ 13

Amounts Awarded Under Performance-Based Bonus Programs during the period

No definition available.

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