Business Segments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2012		Sep. 30, 2011		Sep. 30, 2012		Sep. 30, 2011		Dec. 31, 2011
Segmented Revenues [Abstract]
Total Revenues	$ 1,109,087		$ 1,268,369		$ 3,038,169		$ 2,743,168
Elimination of intersegment revenues	(9,694)		(101,959)		(40,896)		(141,611)
Revenue from external customers	1,099,393		1,166,410		2,997,273		2,601,557
(Loss) Income from Construction Operations [Abstract]
Before Impairment Charge					94,039
Impairment Charge	0		0		(376,574)		0
Income from Construction Operations	54,676		62,036		(282,535)		117,584
Segment reporting information assets [Abstract]
Assets	3,235,458				3,235,458				3,613,127
Building [Member]
Segmented Revenues [Abstract]
Total Revenues	391,531		566,518		1,066,494		1,461,005
Elimination of intersegment revenues	(508)		(72,721)		(4,417)		(81,426)
Revenue from external customers	391,023		493,797		1,062,077		1,379,579
(Loss) Income from Construction Operations [Abstract]
Before Impairment Charge					(2,537)
Impairment Charge					(282,608)
Income from Construction Operations	20,847		8,877		(285,145)		43,704
Segment reporting information assets [Abstract]
Assets	690,188				690,188				1,125,632
Civil [Member]
Segmented Revenues [Abstract]
Total Revenues	350,542		280,446		928,203		557,398
Elimination of intersegment revenues	(4,202)		(3,649)		(8,794)		(9,092)
Revenue from external customers	346,340		276,797		919,409		548,306
(Loss) Income from Construction Operations [Abstract]
Before Impairment Charge					68,884
Impairment Charge					(65,503)
Income from Construction Operations	26,280		23,805		3,381		51,732
Segment reporting information assets [Abstract]
Assets	1,056,837				1,056,837				1,102,471
Specialty Contractors [Member]
Segmented Revenues [Abstract]
Total Revenues	315,270		335,924		858,843		514,809
Elimination of intersegment revenues	0		0		(233)		0
Revenue from external customers	315,270		335,924		858,610		514,809
(Loss) Income from Construction Operations [Abstract]
Before Impairment Charge					53,852
Impairment Charge					(11,489)
Income from Construction Operations	14,236		33,130		42,363		35,812
Segment reporting information assets [Abstract]
Assets	718,383				718,383				597,986
Management Services [Member]
Segmented Revenues [Abstract]
Total Revenues	51,744		85,481		184,629		209,956
Elimination of intersegment revenues	(4,984)		(25,589)		(27,452)		(51,093)
Revenue from external customers	46,760		59,892		157,177		158,863
(Loss) Income from Construction Operations [Abstract]
Before Impairment Charge					6,579
Impairment Charge					(16,974)
Income from Construction Operations	2,841		5,381		(10,395)		14,541
Segment reporting information assets [Abstract]
Assets	184,735				184,735				182,583
Sub Total [Member]
Segmented Revenues [Abstract]
Total Revenues	1,109,087		1,268,369		3,038,169		2,743,168
Elimination of intersegment revenues	(9,694)		(101,959)		(40,896)		(141,611)
Revenue from external customers	1,099,393		1,166,410		2,997,273		2,601,557
(Loss) Income from Construction Operations [Abstract]
Before Impairment Charge					126,778
Impairment Charge					(376,574)
Income from Construction Operations	64,204		71,193		(249,796)		145,789
Segment reporting information assets [Abstract]
Assets	2,650,143				2,650,143				3,008,672
Corporate [Member]
Segmented Revenues [Abstract]
Total Revenues	0		0		0		0
Elimination of intersegment revenues	0		0		0		0
Revenue from external customers	0		0		0		0
(Loss) Income from Construction Operations [Abstract]
Before Impairment Charge					(32,739)	[1]
Impairment Charge					0
Income from Construction Operations	(9,528)	[1]	(9,157)	[1]	(32,739)		(28,205)	[1]
Segment reporting information assets [Abstract]
Assets	$ 585,315	[2]			$ 585,315	[2]			$ 604,455	[2]

[1] Consists primarily of corporate general and administrative expenses.

[2] Consists principally of cash and cash equivalents, corporate transportation equipment, and other investments available for general corporate purposes.