Note 6 - Property and Equipment (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Depreciation, Total	$ 85,900	$ 86,000	$ 56,600
Gain (Loss) on Disposition of Property Plant Equipment, Excluding Oil and Gas Property and Timber Property	(7,123)	(2,029)	(5,822)
Capital Leased Assets, Gross, Total	39,500	46,100
Capital Leases, Lessee Balance Sheet, Assets by Major Class, Accumulated Depreciation	18,100	19,800
Capitalized Computer Software, Amortization	3,100	3,800	$ 7,800
Capitalized Computer Software, Accumulated Amortization	$ 60,200	$ 57,800
Minimum [Member]
Capital Lease, Term	2 years
Maximum [Member]
Capital Lease, Term	8 years 120 days