Note 13 - Subsequent Events - Credit Facility (Details)		Jul. 16, 2018	Jun. 30, 2018
Maximum [Member]
Senior leverage ratio (debt secured by liens/EBITDA)			2.5
Leverage ratio (total debt less unencumbered cash/EBITDA)			4
Interest coverage ratio (EBITDA/interest expense)			3
Maximum [Member] | Subsequent Event [Member]
Senior leverage ratio (debt secured by liens/EBITDA)		2.5
Leverage ratio (total debt less unencumbered cash/EBITDA)	[1]	4
Interest coverage ratio (EBITDA/interest expense)		3
Revolving Credit Facility [Member] | Subsequent Event [Member]
Standby fee per annum on undrawn amounts		0.50%
Revolving Credit Facility [Member] | London Interbank Offered Rate (LIBOR) [Member] | Minimum [Member] | Subsequent Event [Member]
Variable rate		2.25%
Revolving Credit Facility [Member] | London Interbank Offered Rate (LIBOR) [Member] | Maximum [Member] | Subsequent Event [Member]
Variable rate		3.25%
Revolving Credit Facility [Member] | Base Rate [Member] | Minimum [Member] | Subsequent Event [Member]
Variable rate		1.25%
Revolving Credit Facility [Member] | Base Rate [Member] | Maximum [Member] | Subsequent Event [Member]
Variable rate		2.25%

[1] The leverage ratio will change to 4.50:1 from September 30, 2018 to December 31, 2019, and will revert back to 4.00:1 effective January 1, 2020.