Document and Entity Information Document (USD $)	3 Months Ended	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2012	Jun. 30, 2012	Feb. 25, 2013 Class A [Member]	Feb. 25, 2013 Class B [Member]
Document Information [Line Items]
Entity Registrant Name		GENESEE & WYOMING INC.
Entity Registrant Name	0001012620
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2012
Document Fiscal Year Focus	2012
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding				51,412,303	1,728,952
Entity Well-known Seasoned Issuer		Yes
Entity Voluntary Filers		No
Entity Current Reporting Status		Yes
Entity Public Float			$ 2,084,513,852