Goodwill and Intangible Assets (Details) (USD $)	3 Months Ended				6 Months Ended	9 Months Ended			9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended			9 Months Ended		9 Months Ended		9 Months Ended		9 Months Ended
	Sep. 30, 2012	Jun. 30, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2012	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2012 Trade Names (amortizable) [Member]	Dec. 31, 2011 Trade Names (amortizable) [Member]	Sep. 30, 2012 Customer Relationships [Member]	Dec. 31, 2011 Customer Relationships [Member]	Sep. 30, 2012 Construction Contract Backlog [Member]	Dec. 31, 2011 Construction Contract Backlog [Member]	Sep. 30, 2012 Trade Names (Non-amortizable) [Member]	Dec. 31, 2011 Trade Names (Non-amortizable) [Member]	Sep. 30, 2012 Contractor License [Member]	Dec. 31, 2011 Contractor License [Member]	Sep. 30, 2012 Minimum [Member]	Sep. 30, 2012 Maximum [Member]	Sep. 30, 2012 Building Group [Member]	Sep. 30, 2012 Building Group [Member]	Sep. 30, 2012 Civil [Member]	Sep. 30, 2012 Civil [Member]	Sep. 30, 2012 Specialty Contractors [Member]	Sep. 30, 2012 Specialty Contractors [Member]	Sep. 30, 2012 Management Services [Member]	Sep. 30, 2012 Management Services [Member]
Goodwill and Intangible Assets [Abstract]
Indefinite lived intangible assets impairment charge					$ 16,400,000
Finite lived intangible assets impairment charge					39,100,000
Goodwill [Line Items]
Implied market control premium (in hundredths)		42.50%	78.10%
Number of years an acceptable range of market transactions have been observed in the construction and engineering industry						7 years
Weighted-average cost of capital rate (in hundredths)																			15.00%	16.50%
Gross goodwill								1,059,500,000														420,267,000		430,762,000		141,833,000		66,638,000
Accumulated impairment								(166,898,000)														(146,847,000)		0		0		(20,051,000)
Balance at beginning of period					892,602,000	892,602,000															273,420,000		430,762,000		141,833,000		46,587,000
Acquisition related adjustment						(869,000)															0		(869,000)		0		0
Impairment charge					(321,100,000)	(321,087,000)															(262,918,000)		(55,740,000)		0		(2,429,000)
Balance at end of period	570,646,000		892,602,000			570,646,000															10,502,000		374,153,000		141,833,000		44,158,000
Indefinite-lived Intangible Assets [Line Items]
Cost															117,600,000	117,600,000	6,000,000	6,000,000
Accumulated amortization															0	0	0	0
Accumulated impairment charge															(67,190,000)	(56,100,000)	(6,000,000)	(680,000)
Carrying value															50,410,000	61,500,000	0	5,320,000
Weighted average amortization period															Indefinite	Indefinite	N/A	Indefinite
Finite-Lived Intangible Assets [Line Items]
Cost									74,350,000	74,350,000	39,800,000	39,800,000	73,706,000	71,140,000
Accumulated amortization									(3,232,000)	(788,000)	(12,708,000)	(10,585,000)	(52,357,000)	(41,938,000)
Accumulated impairment charge									(23,232,000)	(800,000)	(16,645,000)	0	0	0
Carrying value									47,886,000	72,762,000	10,447,000	29,215,000	21,349,000	29,202,000
Weighted average amortization period									20 years	20 years	11 years 4 months 24 days	11 years 7 months 6 days	3 years 7 months 6 days	2 years 10 months 24 days
Total intangible assets [Abstract]
Cost	311,456,000		308,890,000			311,456,000
Accumulated amortization	(68,297,000)		(53,311,000)			(68,297,000)
Accumulated impairment charge	(113,067,000)		(57,580,000)			(113,067,000)
Carrying value	130,092,000		197,999,000			130,092,000
Amortization Expense [Abstract]
Amortization expense during period	3,600,000			2,900,000		15,000,000	6,900,000
Amortization expense, remainder of 2012	3,300,000					3,300,000
Amortization expense, 2013	13,100,000					13,100,000
Amortization expense, 2014	11,900,000					11,900,000
Amortization expense, 2015	5,300,000					5,300,000
Amortization expense, 2016	3,500,000					3,500,000
Amortization expense, thereafter	$ 42,600,000					$ 42,600,000