Equity Investment Equity Investment (Details) (USD $)	3 Months Ended								12 Months Ended				3 Months Ended		12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Oct. 02, 2012 RailAmerica [Member]	Dec. 28, 2012 RailAmerica [Member]	Dec. 31, 2012 RailAmerica [Member]	Dec. 31, 2012 RailAmerica [Member]
Acquisition Purchase Price Per Share												$ 27.50
Income from equity investment in RailAmerica, net									$ 15,557,000	$ 0	$ 0				$ 15,600,000
NET INCOME AVAILABLE TO COMMON STOCKHOLDERS	9,021,000	(19,567,000)	36,363,000	22,241,000	33,275,000	32,942,000	31,145,000	22,122,000					15,806,000
Equity investment intercompany elimination														200,000
Acquisition/integration costs														$ 3,500,000