Note 7 - Contract Assets and Liabilities (Details Textual) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Contract with Customer, Liability, Revenue Recognized	$ 13,200	$ 600	$ 118,800	$ 103,300
Contract with Customer, Asset, Cumulative Catch-up Adjustment to Revenue, Change in Estimate of Transaction Price	32,800	25,300	117,600	86,200
Aggregate Affirmative Claim Recovery Estimate Included in Contract Asset and Liability	$ 60,600	$ 37,200	60,600	$ 37,200	$ 45,100
Contract Receivable Retainage Uncollectible Amount			$ 0