Changes in Operations (Details) (AZER [Member], USD $)	Sep. 01, 2011 track_miles trackage_rights_miles locomotives rail_lines employees
AZER [Member]
Business Acquisition [Line Items]
Cost of acquired entity	$ 90,100,000
Working capital adjustment	600,000
Acquisition costs	500,000
Number of employees acquired	43
Number of locomotives acquired	10
Number of rail lines acquired	2
Track miles acquired	200
Trackage rights miles acquired	52
Accounts receivable	2,799,000
Prepaid expense and other	2,319,000
Property and equipment	90,120,000
Total assets	95,238,000
Accounts payable	2,275,000
Accrued expenses	3,468,000
Net assets	$ 89,495,000