Note 4 - Goodwill and Other Intangible Assets (Details Textual) - USD ($)	3 Months Ended	9 Months Ended
	Jun. 30, 2017	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015
Indefinite-Lived Intangible Assets (Excluding Goodwill)		$ 298,383,000	$ 298,394,000	$ 298,383,000	$ 298,394,000
Goodwill, Impairment Loss		1,117,000
Goodwill		46,225,000	47,342,000	47,342,000	$ 47,342,000
Goodwill, Impaired, Accumulated Impairment Loss		149,700,000		148,600,000
Other Intangible Assets, Impaired, Accumulated Impairment Loss		99,900,000		99,900,000
Unrecognized [Member]
Goodwill, Impairment Loss		0
SMI Properties [Member]
Goodwill	$ 0
Motorsports Event Segment [Member]
Goodwill, Impairment Loss	1,117,000	1,117,000
Goodwill, Impairment Loss, Tax Benefit	$ 419,000
Goodwill		46,225,000		47,342,000
NHMS and TMS [Member] | Nonamortizable Race Event Sanctioning and Renewal Agreements [Member]
Indefinite-Lived Intangible Assets (Excluding Goodwill)		$ 199,600,000		$ 98,800,000