Note 11 - Construction Joint Ventures (Details Textual) $ in Thousands	3 Months Ended			6 Months Ended		9 Months Ended
	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)
Contract with Customer, Liability, Total	$ 106,010		$ 117,759	$ 106,010		$ 106,010	$ 117,759	$ 105,449
Contract Value of Active Construction Joint Venture Projects	3,300,000			3,300,000		3,300,000
Revenue from Contract with Customer, Including Assessed Tax	1,088,110		1,055,591			2,497,451	2,426,089
Retained Earnings (Accumulated Deficit), Ending Balance	656,487		786,936	656,487		656,487	786,936	787,356
Unconsolidated Construction Joint Venture Cost Of Revenue		$ 171,000			$ 302,500
Unconsolidated Construction Joint Venture Gross Profit (Loss)		134,200			133,200
Unconsolidated Construction Joint Venture Net Income (Loss)		133,300	(3,100)	(40,200)	132,800	(173,008)	(16,343)
Increase (Decrease) in Other Accounts Payable and Accrued Liabilities						(768)	37,352
Net Income (Loss) Attributable to Parent, Total	20,488		55,672			(111,922)	35,864
Unconsolidated Construction Corporate Joint Venture [Member]
Net Income (Loss) Attributable to Parent, Total	(19,600)		(47,600)			(33,300)	(162,000)
Previously Reported [Member]
Unconsolidated Construction Joint Venture Cost Of Revenue		144,000			275,500
Unconsolidated Construction Joint Venture Gross Profit (Loss)		107,200			106,200
Unconsolidated Construction Joint Venture Net Income (Loss)					105,800
Restatement Adjustment [Member]
Unconsolidated Construction Joint Venture Net Income (Loss)					(27,000)
Increase (Decrease) in Other Accounts Payable and Accrued Liabilities					$ (27,000)
Unconsolidated Construction Corporate Joint Venture [Member]
Contract with Customer, Liability, Total	$ 812,100			$ 812,100		$ 812,100
Number of Active Joint Venture Projects	9			9		9
Contract Value of Active Construction Joint Venture Projects	$ 11,500,000			$ 11,500,000		$ 11,500,000
Affirmative Claim Recovery Estimate	96,800		67,100	96,800		96,800	67,100	78,100
Back Charge Claims	11,800		12,500	11,800		11,800	12,500	15,600
Retained Earnings (Accumulated Deficit), Ending Balance	(65,100)		(11,600)	(65,100)		(65,100)	(11,600)	(11,500)
Unconsolidated Construction Corporate Joint Venture [Member] | Previously Reported [Member]
Unconsolidated Construction Joint Venture Net Income (Loss)		$ 106,300
Unconsolidated Construction Corporate Joint Venture [Member] | Minimum [Member]
Contract with Customer, Liability, Total	1,700			1,700		1,700
Contract Value of Active Construction Joint Venture Projects	$ 85,200,000			$ 85,200,000		$ 85,200,000
Equity Method Investment, Ownership Percentage	20.00%			20.00%		20.00%
Unconsolidated Construction Corporate Joint Venture [Member] | Maximum [Member]
Contract with Customer, Liability, Total	$ 226,000			$ 226,000		$ 226,000
Contract Value of Active Construction Joint Venture Projects	$ 3,800,000			$ 3,800,000		$ 3,800,000
Equity Method Investment, Ownership Percentage	50.00%			50.00%		50.00%
Unconsolidated Construction Corporate Joint Venture [Member] | Performance Guarantee [Member]
Guarantor Obligations, Maximum Exposure, Undiscounted	$ 1,000,000			$ 1,000,000		$ 1,000,000
Guarantor Obligations, Current Carrying Value	81,900		88,600	81,900		81,900	88,600	$ 88,200
Unconsolidated Construction Corporate Joint Venture [Member] | Construction [Member]
Contract with Customer, Liability, Total	2,800,000			2,800,000		2,800,000
Co-venturer [Member] | Performance Guarantee [Member]
Guarantor Obligations, Maximum Exposure, Undiscounted	1,800,000			1,800,000		1,800,000
Consolidated Construction Corporate Joint Venture [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Contract with Customer, Liability, Total	$ 338,100			$ 338,100		$ 338,100
Number of Active Joint Venture Projects	7			7		7
Contract Value of Active Construction Joint Venture Projects	$ 1,200,000			$ 1,200,000		$ 1,200,000
Revenue from Contract with Customer, Including Assessed Tax	71,100		$ 61,600			217,000	173,100
Net Cash Provided by (Used in) Continuing Operations, Total						19,300	$ 31,500
Consolidated Construction Corporate Joint Venture [Member] | Variable Interest Entity, Primary Beneficiary [Member] | Minimum [Member]
Contract with Customer, Liability, Total	300			300		300
Contract Value of Active Construction Joint Venture Projects	700			700		$ 700
Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage						50.00%
Consolidated Construction Corporate Joint Venture [Member] | Variable Interest Entity, Primary Beneficiary [Member] | Maximum [Member]
Contract with Customer, Liability, Total	137,200			137,200		$ 137,200
Contract Value of Active Construction Joint Venture Projects	$ 410,500			$ 410,500		$ 410,500
Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage						65.00%