Quarterly Results - (unaudited) (Details 2) (USD $)	12 Months Ended			3 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Sep. 30, 2011 Nashville Superspeedway
Quarterly results
Non-cash impairment charge		$ 15,687,000	$ 809,000	$ 15,687,000
Non-cash impairment charges after income taxes				10,197,000
Provision for contingent obligation	(321,000)	2,250,000		2,245,000
Provision for contingent obligation after income taxes				$ 1,333,000