Revisions in Estimates (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Change in Accounting Estimate [Line Items]
Financial Effect on Future Periods	$ 0		$ 0
Amount Considered Significant on Individual Project Gross Profit	1,000,000	1,000,000	1,000,000	1,000,000
Contracts Accounted for under Percentage of Completion [Member] | Large Project Construction [Member]
Change in Accounting Estimate [Line Items]
Increase (Decrease) on Project Profitability	2,700,000	(100,000)	7,900,000	6,500,000
Contracts Accounted for under Percentage of Completion [Member] | Large Project Construction [Member] | Noncontrolling Interest [Member]
Change in Accounting Estimate [Line Items]
Increase (Decrease) on Project Profitability	1,000,000	100,000	600,000	1,500,000
Upward Estimate Change [Member] | Large Project Construction [Member]
Change in Accounting Estimate [Line Items]
Number of Projects with Estimate Changes	5	2	6	6
Increase (Decrease) on Project Profitability	8,800,000	4,200,000	17,700,000	11,600,000
Upward Estimate Change [Member] | Large Project Construction [Member] | Minimum [Member]
Change in Accounting Estimate [Line Items]
Range Of Effect On Gross Profit	1,000,000	1,400,000	1,400,000	1,000,000
Upward Estimate Change [Member] | Large Project Construction [Member] | Maximum [Member]
Change in Accounting Estimate [Line Items]
Range Of Effect On Gross Profit	2,600,000	2,800,000	4,200,000	4,200,000
Upward Estimate Change [Member] | Construction [Member]
Change in Accounting Estimate [Line Items]
Number of Projects with Estimate Changes	2	2	4	3
Increase (Decrease) on Project Profitability	2,700,000	5,100,000	7,000,000	6,500,000
Upward Estimate Change [Member] | Construction [Member] | Minimum [Member]
Change in Accounting Estimate [Line Items]
Range Of Effect On Gross Profit	1,300,000	2,200,000	1,100,000	1,000,000
Upward Estimate Change [Member] | Construction [Member] | Maximum [Member]
Change in Accounting Estimate [Line Items]
Range Of Effect On Gross Profit	1,400,000	2,900,000	2,900,000	2,900,000
Downward Estimate Change [Member] | Large Project Construction [Member]
Change in Accounting Estimate [Line Items]
Number of Projects with Estimate Changes	3	2	2	2
Increase (Decrease) on Project Profitability	(6,100,000)	(4,300,000)	(9,800,000)	(5,100,000)
Downward Estimate Change [Member] | Large Project Construction [Member] | Minimum [Member]
Change in Accounting Estimate [Line Items]
Range Of Effect On Gross Profit	(1,700,000)	(1,900,000)	(4,200,000)	(2,200,000)
Downward Estimate Change [Member] | Large Project Construction [Member] | Maximum [Member]
Change in Accounting Estimate [Line Items]
Range Of Effect On Gross Profit	(2,400,000)	(2,400,000)	(5,600,000)	(2,900,000)
Downward Estimate Change [Member] | Construction [Member]
Change in Accounting Estimate [Line Items]
Number of Projects with Estimate Changes	2	2	3	3
Increase (Decrease) on Project Profitability	(4,000,000)	(4,400,000)	(5,400,000)	(6,900,000)
Downward Estimate Change [Member] | Construction [Member] | Minimum [Member]
Change in Accounting Estimate [Line Items]
Range Of Effect On Gross Profit	(1,400,000)	(2,200,000)	(1,400,000)	(1,900,000)
Downward Estimate Change [Member] | Construction [Member] | Maximum [Member]
Change in Accounting Estimate [Line Items]
Range Of Effect On Gross Profit	(2,600,000)	(2,200,000)	(2,600,000)	(2,700,000)
Construction [Member]
Change in Accounting Estimate [Line Items]
Increase (Decrease) on Project Profitability	$ (1,300,000)	$ 700,000	$ 1,600,000	$ (400,000)