Revisions in Estimates (Details) (USD $)	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Change in Accounting Estimate [Line Items]
Financial Effect on Future Periods	$ 0
Amount Considered Significant on Individual Project Gross Profit	1,000,000	1,000,000
Construction [Member]
Change in Accounting Estimate [Line Items]
Increase (Decrease) on Project Profitability	200,000	(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	(4,400,000)	(5,900,000)
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	(1,300,000)	(400,000)
Upward Estimate Change [Member] | Construction [Member]
Change in Accounting Estimate [Line Items]
Number of Projects with Estimate Changes	2	1
Increase (Decrease) on Project Profitability	(2,800,000)	(1,000,000)
Upward Estimate Change [Member] | Construction [Member] | Minimum [Member]
Change in Accounting Estimate [Line Items]
Range Of Effect On Gross Profit	1,000,000	1,000,000
Upward Estimate Change [Member] | Construction [Member] | Maximum [Member]
Change in Accounting Estimate [Line Items]
Range Of Effect On Gross Profit	1,800,000	1,000,000
Upward Estimate Change [Member] | Large Project Construction [Member]
Change in Accounting Estimate [Line Items]
Number of Projects with Estimate Changes	4	3
Increase (Decrease) on Project Profitability	(8,100,000)	(8,800,000)
Upward Estimate Change [Member] | Large Project Construction [Member] | Minimum [Member]
Change in Accounting Estimate [Line Items]
Range Of Effect On Gross Profit	1,600,000	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	2,400,000	4,200,000
Downward Estimate Change [Member] | Construction [Member]
Change in Accounting Estimate [Line Items]
Number of Projects with Estimate Changes	1	0
Increase (Decrease) on Project Profitability	3,000,000	0
Downward Estimate Change [Member] | Construction [Member] | Minimum [Member]
Change in Accounting Estimate [Line Items]
Range Of Effect On Gross Profit	(3,000,000)	0
Downward Estimate Change [Member] | Construction [Member] | Maximum [Member]
Change in Accounting Estimate [Line Items]
Range Of Effect On Gross Profit	(3,000,000)	0
Downward Estimate Change [Member] | Large Project Construction [Member]
Change in Accounting Estimate [Line Items]
Number of Projects with Estimate Changes	2	1
Increase (Decrease) on Project Profitability	3,700,000	(2,900,000)
Downward Estimate Change [Member] | Large Project Construction [Member] | Minimum [Member]
Change in Accounting Estimate [Line Items]
Range Of Effect On Gross Profit	(1,500,000)	(2,900,000)
Downward Estimate Change [Member] | Large Project Construction [Member] | Maximum [Member]
Change in Accounting Estimate [Line Items]
Range Of Effect On Gross Profit	$ (2,200,000)	$ (2,900,000)