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

12 Months Ended

Dec. 31, 2016

Notes Tables

Schedule of Principal Transactions Revenue [Table Text Block]

	Year Ended December 31,
	2016			2015			2014
Trade revenue	$	2,069		$	2,299		$	2,174
Trade expense		(1,997	)		(2,188	)		(2,287	)
Net trade income (loss)	$	72		$	111		$	(113	)

Property, Plant and Equipment [Table Text Block]

							Estimated
	December 31,						Useful Lives
	2016			2015			(in years)
Property and equipment:
Land	$	44,611		$	36,529
Buildings and improvements		139,078			85,626			7	to	40
Equipment		471,798			420,380			3	to	20
		655,487			542,535
Accumulated depreciation		(329,394	)		(308,060	)
Total property and equipment, net	$	326,093		$	234,475

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

	Year Ended December 31,
	2016		2015		2014
Weighted-average shares outstanding – basic		71,848		68,330		57,862
Weighted-average shares underlying stock options and restricted shares		916		657		502
Weighted-average shares outstanding - diluted		72,764		68,987		58,364

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

	December 31,
	2016			2015
Accumulated balances of items included in accumulated other comprehensive loss:
Increase in pension liability	$	(28,926	)	$	(28,334	)
Income tax benefit		(11,281	)		(11,050	)
Accumulated other comprehensive loss	$	(17,645	)	$	(17,284	)