Note 8 - Accounting for Share-based Payment Arrangement Compensation (Details Textual) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Stock or Unit Option Plan Expense			$ 730,000	$ 668,000
Income Tax Expense (Benefit)	$ (6,303,000)	$ (6,008,000)	(11,886,000)	(11,725,000)
Net Cash Provided by (Used in) Operating Activities			65,220,000	80,151,000
Net Cash Provided by (Used in) Financing Activities			8,685,000	40,699,000
Accounting Standards Update 2016-09 [Member]
Income Tax Expense (Benefit)			$ (132,000)
Net Cash Provided by (Used in) Operating Activities				30,000
Net Cash Provided by (Used in) Financing Activities				$ (30,000)