Consolidated Statements of Changes in Equity Statement (USD $)	Total	Class A common stock [Member]	Class B common stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]	Non-controlling Interest [Member]
BALANCE, at Dec. 31, 2011	$ 960,634,000	$ 527,000	$ 22,000	$ 385,473,000	$ 741,669,000	$ 37,895,000	$ (204,952,000)	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
NET INCOME	52,433,000	0	0	0	52,433,000	0	0	0
Other comprehensive income/(loss)	9,376,000	0	0	0	0	9,376,000	0	0
Dividends paid on Series A-1 Preferred Stock	(4,375,000)	0	0	0	(4,375,000)	0	0	0
Proceeds from employee stock purchases	19,320,000	9,000	0	19,311,000	0	0	0	0
Conversion of Class B common stock to Class A common stock	0	5,000	(5,000)	0	0	0	0	0
Compensation cost related to equity awards	12,151,000	0	0	12,151,000	0	0	0	0
Compensation costs related to equity awards included in income from equity investment in RailAmerica	2,816,000	0	0	2,816,000	0	0	0	0
Tax benefits from share-based compensation	4,795,000	0	0	4,795,000	0	0	0	0
Net proceeds from Class A common stock issuance	234,340,000	38,000	0	234,302,000	0	0	0	0
TEU Purchase Contracts issuance proceeds, net of issuance costs	191,428,000	0	0	191,428,000	0	0	0	0
RailAmerica acquisition consideration for share-based awards	15,400,000	0	0	15,400,000	0	0	0	0
Treasury stock acquisitions from equity awards	(4,314,000)	0	0	0	0	0	(4,314,000)	0
Settlement of deferred stock awards	933,000	0	0	933,000	0	0	0	0
Noncontrolling interest	5,525,000	0	0	0	0	0	0	5,525,000
BALANCE, at Dec. 31, 2012	1,500,462,000	579,000	17,000	866,609,000	789,727,000	47,271,000	(209,266,000)	5,525,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
NET INCOME	272,091,000	0	0	0	271,296,000	0	0	795,000
Other comprehensive income/(loss)	(41,182,000)	0	0	0	0	(41,182,000)	0	0
Dividends paid on Series A-1 Preferred Stock	(2,139,000)	0	0	0	(2,139,000)	0	0	0
Proceeds from employee stock purchases	12,510,000	6,000	0	12,504,000	0	0	0	0
Conversion of Class B common stock to Class A common stock	0	1,000	(1,000)	0	0	0	0	0
Compensation cost related to equity awards	16,951,000	0	0	16,951,000	0	0	0	0
Conversion of 5,984,232 shares Series A-1 Preferred Stock to Class A common stock	399,389,000	60,000	0	399,329,000	0	0	0	0
Tax benefits from share-based compensation	6,854,000	0	0	6,854,000	0	0	0	0
Treasury stock acquisitions from equity awards	(11,095,000)	0	0	0	0	0	(11,095,000)	0
Settlement of deferred stock awards	274,000	0	0	274,000	0	0	0	0
Noncontrolling interest	(5,045,000)	0	0	0	0	0	0	(5,045,000)
BALANCE, at Dec. 31, 2013	$ 2,149,070,000	$ 646,000	$ 16,000	$ 1,302,521,000	$ 1,058,884,000	$ 6,089,000	$ (220,361,000)	$ 1,275,000