Note 3 - Recent Accounting Pronouncements (Details Textual) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Jan. 01, 2020	Dec. 31, 2019
Retained Earnings (Accumulated Deficit), Ending Balance	$ 1,710,994			$ 1,710,994			$ 1,659,153
Provision for Loan and Lease Losses, Total	25,000	$ 25,000	$ 0	$ 50,000	$ 0
Cumulative Effect, Period of Adoption, Adjustment [Member] | Accounting Standards Update 2016-13 [Member] | Minimum [Member]
Retained Earnings (Accumulated Deficit), Ending Balance						$ 10,000
Accounts Receivable, Allowance for Credit Loss, Ending Balance						15,000
Accounts Receivable, Credit Loss Expense (Reversal)	5,000	10,000
Cumulative Effect, Period of Adoption, Adjustment [Member] | Accounting Standards Update 2016-13 [Member] | Maximum [Member]
Retained Earnings (Accumulated Deficit), Ending Balance						12,000
Accounts Receivable, Allowance for Credit Loss, Ending Balance						$ 17,000
Accounts Receivable, Credit Loss Expense (Reversal)	$ 10,000	$ 15,000