Note 2 - Acquisitions and Divestitures - Schedule of Acquired Property and Equipment of Valley Forge Convention Center Partners (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($)
Valley Forge Convention Center Partners, L.P. [Member]
Property and Equipment, Recorded Amount	$ 57,118
Land [Member] | Valley Forge Convention Center Partners, L.P. [Member]
Property and Equipment, Recorded Amount	$ 15,150
Building and Building Improvements [Member] | Minimum [Member]
Property and Equipment, Useful Life (Year)	3 years
Building and Building Improvements [Member] | Maximum [Member]
Property and Equipment, Useful Life (Year)	40 years
Building and Building Improvements [Member] | Valley Forge Convention Center Partners, L.P. [Member]
Property and Equipment, Recorded Amount	$ 32,908
Building and Building Improvements [Member] | Valley Forge Convention Center Partners, L.P. [Member] | Minimum [Member]
Property and Equipment, Useful Life (Year)	15 years
Furniture and Fixtures [Member] | Minimum [Member]
Property and Equipment, Useful Life (Year)	1 year
Furniture and Fixtures [Member] | Maximum [Member]
Property and Equipment, Useful Life (Year)	10 years
Furniture and Fixtures [Member] | Valley Forge Convention Center Partners, L.P. [Member]
Property and Equipment, Recorded Amount	$ 9,060
Furniture and Fixtures [Member] | Valley Forge Convention Center Partners, L.P. [Member] | Minimum [Member]
Property and Equipment, Useful Life (Year)	2 years