Note 10 - Segment Information, Significant Customers, Industry Concentration and Geographic Areas (Tables)

12 Months Ended

Dec. 31, 2021

Notes Tables

Reconciliation of Revenue from Segments to Consolidated [Table Text Block]

	Year Ended December 31,
	2021					2020					2019
	(in thousands)
	Amount		Percent			Amount		Percent			Amount		Percent
United States - domestic shipments	$	474,291		67.9		$	316,542		66.1		$	326,559		63.5
Shipments to or from Mexico		223,315		32.0			161,412		33.7			186,392		36.3
Shipments to or from Canada		891		0.1			1,156		0.2			1,226		0.2
Total Operating Revenues	$	698,497		100	%	$	479,110		100	%	$	514,177		100	%