Note 8 - Inventories - Fair Value of Impaired Inventory (Details) $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Impairment Data; Total Subdivisions Tested	14	16	12	16	20	17	17	24	23	33	35	33
Impairment Data; Inventory Impairments	$ 325	$ 0	$ 0	$ 610	$ 10,002	$ 11,098	$ 200	$ 550	$ 620	$ 4,540	$ 0	$ 4,850	$ 935	$ 21,850	$ 10,010
Impairment Data; Fair Value of Inventory After Impairments	$ 3,948	$ 0	$ 0	$ 10,476	$ 32,248	$ 29,874	$ 767	$ 5,223	$ 14,245	$ 52,190	$ 0	$ 19,952
Impairment Data; Number of Subdivisions Impaired	2	0	0	2	10	2	1	2	2	9	0	2
Measurement Input, Discount Rate [Member]
Quantitative Data; Discount Rate							0.12	0.12
Measurement Input, Discount Rate [Member] | Minimum [Member]
Quantitative Data; Discount Rate					0.12	0.12			0.10	0.10		0.12		0.12	0.10
Measurement Input, Discount Rate [Member] | Maximum [Member]
Quantitative Data; Discount Rate					0.18	0.18			0.12	0.15		0.18		0.18	0.12