Note 1 - Description of Business and Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2015

Notes Tables

Schedule of Principal Transactions Revenue [Table Text Block]

	Year Ended December 31,
	2015			2014			2013
Trade revenue	$	2,299		$	2,174		$	1,390
Trade expense		(2,188	)		(2,287	)		(1,262	)
Net trade income (loss)	$	111		$	(113	)	$	128

Property, Plant and Equipment [Table Text Block]

	December 31,						Estimated Useful Lives
	2015			2014			(in years)
Property and equipment:
Land	$	36,529		$	32,085
Buildings and improvements		85,626			77,477		7	to	40
Equipment		420,380			394,569		3	to	20
		542,535			504,131
Accumulated depreciation		(308,060	)		(282,320	)
Total property and equipment, net	$	234,475		$	221,811

Schedule of Weighted Average Number of Shares [Table Text Block]

	Year Ended December 31,
	2015		2014		2013
Weighted-average shares outstanding – basic		68,330		57,862		57,630
Weighted-average shares underlying stock options and restricted shares		657		502		342
Weighted-average shares outstanding - diluted		68,987		58,364		57,972

Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]

	December 31,
	2015			2014
Accumulated balances of items included in accumulated other comprehensive loss:
Increase in pension liability	$	(28,334	)	$	(34,117	)
Income tax benefit		(11,050	)		(13,305	)
Accumulated other comprehensive loss	$	(17,284	)	$	(20,812	)