Note 9 - Debt, Credit Facilities and Leases - Credit Facility (Details)	3 Months Ended
	Mar. 31, 2019
Maximum [Member]
Senior leverage ratio (debt secured by liens/EBITDA)	2.5
Leverage ratio (total debt less unencumbered cash/EBITDA)	4.5	[1]
Interest coverage ratio (EBITDA/interest expense)	3
New Facility [Member]
Standby fee per annum on undrawn amounts	0.50%
New Facility [Member] | Minimum [Member] | London Interbank Offered Rate (LIBOR) [Member]
Variable rate	2.25%
New Facility [Member] | Minimum [Member] | Base Rate [Member]
Variable rate	1.25%
New Facility [Member] | Maximum [Member] | London Interbank Offered Rate (LIBOR) [Member]
Variable rate	3.25%
New Facility [Member] | Maximum [Member] | Base Rate [Member]
Variable rate	2.25%

[1] The leverage ratio changed to 5.00:1 effective April 1, 2019, will return to 4.50:1 effective October 1, 2019, and then change to 4.00:1 effective January 1, 2020.