Note 11 - Construction Joint Ventures (Details Textual) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022 USD ($)	Jun. 30, 2021 USD ($)	Jun. 30, 2022 USD ($)	Jun. 30, 2021 USD ($)	Mar. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Contract Value of Active Construction Joint Venture Projects	$ 2,700,000		$ 2,700,000
Contract with Customer, Liability, Total	179,322	$ 166,415	179,322	$ 166,415		$ 200,041
Revenue from Contract with Customer, Including Assessed Tax	768,286	834,671	1,315,872	1,401,003
Retained Earnings (Accumulated Deficit), Total	$ 413,931	401,061	$ 413,931	401,061		410,831
Minimum [Member] | Unconsolidated Construction Corporate Joint Venture [Member]
Equity Method Investment, Ownership Percentage	20.00%		20.00%
Maximum [Member] | Unconsolidated Construction Corporate Joint Venture [Member]
Equity Method Investment, Ownership Percentage	50.00%		50.00%
Unconsolidated Construction Corporate Joint Venture [Member]
Number of Active Joint Venture Projects	8		8
Contract Value of Active Construction Joint Venture Projects	$ 9,700,000		$ 9,700,000
Contract with Customer, Liability, Total	110,300		110,300
Affirmative Claim Recovery Estimate	109,500	96,700	109,500	96,700		103,800
Back Charge Claims	2,900	14,100	2,900	14,100		10,700
Retained Earnings (Accumulated Deficit), Total	12,700	33,600	12,700	33,600		$ 28,600
Unconsolidated Construction Corporate Joint Venture [Member] | Minimum [Member]
Contract Value of Active Construction Joint Venture Projects	12,300		12,300
Contract with Customer, Liability, Total	1,100		1,100
Unconsolidated Construction Corporate Joint Venture [Member] | Maximum [Member]
Contract Value of Active Construction Joint Venture Projects	3,800		3,800
Contract with Customer, Liability, Total	34,800		34,800
Unconsolidated Construction Corporate Joint Venture [Member] | Performance Guarantee [Member]
Guarantor Obligations, Maximum Exposure, Undiscounted	110,300		110,300
Guarantor Obligations, Current Carrying Value	77,400	82,300	77,400	82,300	$ 82,100
Co-venturer [Member] | Performance Guarantee [Member]
Guarantor Obligations, Maximum Exposure, Undiscounted	199,400		199,400
Consolidated Construction Corporate Joint Venture [Member]
Contract Value of Active Construction Joint Venture Projects	$ 1,000,000		$ 1,000,000
Consolidated Construction Corporate Joint Venture [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Number of Active Joint Venture Projects	9		9
Contract Value of Active Construction Joint Venture Projects	$ 1,800,000		$ 1,800,000
Contract with Customer, Liability, Total	225,900		225,900
Revenue from Contract with Customer, Including Assessed Tax	119,400	114,900	227,000	197,500
Net Cash Provided by (Used in) Continuing Operations, Total			13,400	19,400
Consolidated Construction Corporate Joint Venture [Member] | Variable Interest Entity, Primary Beneficiary [Member] | Minimum [Member]
Contract Value of Active Construction Joint Venture Projects	12,100		12,100
Contract with Customer, Liability, Total	4,700		$ 4,700
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 Value of Active Construction Joint Venture Projects	439,400		$ 439,400
Contract with Customer, Liability, Total	56,200		$ 56,200
Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage			70.00%
Construction [Member]
Revenue from Contract with Customer, Including Assessed Tax	$ 632,260	$ 713,425	$ 1,107,195	$ 1,220,396
Construction [Member] | Unconsolidated Construction Corporate Joint Venture [Member]
Contract with Customer, Liability, Revenue Recognized			$ 309,700