Business Operations - Assets held for sale (Details)					1 Months Ended	3 Months Ended			12 Months Ended
	Jul. 26, 2019 USD ($) a	Feb. 28, 2019 USD ($) a	Mar. 02, 2018 USD ($)	Sep. 01, 2017 USD ($) a	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2019 USD ($) a	Dec. 31, 2018 USD ($)	Aug. 17, 2017 USD ($) a
Business Operations
Fair value of land										$ 531,000
Non-refundable deposit									$ 500,000
Long term assets held for sale									21,282,000	23,567,000
Gain (loss) on sale of land									4,325,000	2,413,000
Nashville Superspeedway | Assets held for sale
Business Operations
Acres | a		7.63
Long term assets held for sale									$ 21,282,000	$ 23,567,000
Proceeds, less closing costs		$ 267,000
Gain (loss) on sale of land						$ (4,186,000)	$ 139,000	$ 2,512,000
Nashville Superspeedway | Land
Business Operations
Acres | a	133			88.03					97.17		147
Purchase price (per acre)											$ 35,000
Option purchase price (per acre)				$ 55,000					$ 66,685
Non-refundable deposit									$ 500,000
Period of option to execute the agreement				3 years
Proceeds, less closing costs	$ 6,397,000		$ 4,945,000
Net proceeds after taxes	5,314,000		4,150,000
Gain (loss) on sale of land	$ 4,186,000		$ 2,512,000
Nashville Superspeedway | Land | Minimum | Assets held for sale
Business Operations
Acres | a									1,000
Parcel of land near St. Louis | Assets held for sale
Business Operations
Proceeds, less closing costs							$ 531,000
Gain (loss) on sale of land					$ (99,000)