Note 3 - Recent Accounting Pronouncements (Details Textual) - USD ($) $ in Thousands	3 Months Ended				9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Jan. 01, 2020	Dec. 31, 2019
Retained Earnings (Accumulated Deficit), Ending Balance	$ 1,743,106				$ 1,743,106			$ 1,659,153
Accounts Receivable, Credit Loss Expense (Reversal)	12,500
Provision for Loan and Lease Losses, Total	12,500	$ 25,000	$ 25,000	$ (2,000)	$ 62,500	$ (2,000)
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)	15,000	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)	$ 25,000	$ 10,000	$ 15,000