Note 4 - Revisions in Estimates - Summary of Impact of Revisions in Estimates to Gross Profit (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)
Range of reduction in gross profit from each project, net	$ (91,432)	$ (144,491)	$ (79,506)	$ (281,143)
Decrease to project profitability	(25,387)	(67,789)	$ 140,580	$ (50,711)
Estimated Cost Recovery of Customer Affirmative Claims and Back Charges [Member]
Range of reduction in gross profit from each project, net	$ 5,000	$ 5,000
Number of projects with downward estimate changes	6	2	9	4
Decrease to project profitability	$ 80,700	$ 19,300	$ 264,100	$ 57,800
Estimated Cost Recovery of Customer Affirmative Claims and Back Charges [Member] | Maximum [Member]
Range of reduction in gross profit from each project, net	30,900	12,000	92,600	25,600
Estimated Cost Recovery of Customer Affirmative Claims and Back Charges [Member] | Minimum [Member]
Range of reduction in gross profit from each project, net	$ 5,400	$ 7,300	$ 6,000	$ 5,200