Subsequent Events Providence and Worchester Railroad (Details) - Providence and Worcester Railroad [Member] - Subsequent Event [Member] $ / shares in Units, $ in Millions		3 Months Ended
	Nov. 01, 2016 USD ($) mile employee carload locomotive port a $ / shares	Dec. 31, 2016
Subsequent Event [Line Items]
Business Acquisition, Effective Date of Acquisition		Nov. 01, 2016
Business Acquisition, Share Price | $ / shares	$ 25.00
Cash consideration | $	$ 126.2
Number of employees | employee	140
Locomotives | locomotive	32
Track Miles Owned | mile	163
Track Miles Leased | mile	350
Annual carloads transported | carload	43,000
Number of Ports Operated | port	3
Acres of undeveloped land expected to sell | a	45
Amount Invested for Undeveloped Land Purchase | $	$ 12.0