Revisions in Estimates (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 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	(300,000)	6,300,000	5,200,000	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		500,000	400,000	1,900,000
Upward Estimate Change [Member] | Large Project Construction [Member]
Change in Accounting Estimate [Line Items]
Number of Projects with Estimate Changes	1	3	4	4
Increase (Decrease) on Project Profitability	1,300,000	6,300,000	11,000,000	10,600,000
Upward Estimate Change [Member] | Large Project Construction [Member] | Minimum [Member]
Change in Accounting Estimate [Line Items]
Range Of Effect On Gross Profit	1,300,000	1,100,000	1,000,000	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	1,300,000	4,000,000	4,200,000	4,200,000
Upward Estimate Change [Member] | Construction [Member]
Change in Accounting Estimate [Line Items]
Number of Projects with Estimate Changes	1	0	2	0
Increase (Decrease) on Project Profitability	1,400,000	0	2,900,000	0
Upward Estimate Change [Member] | Construction [Member] | Minimum [Member]
Change in Accounting Estimate [Line Items]
Range Of Effect On Gross Profit	1,400,000	0	1,400,000	0
Upward Estimate Change [Member] | Construction [Member] | Maximum [Member]
Change in Accounting Estimate [Line Items]
Range Of Effect On Gross Profit	1,400,000	0	1,500,000	0
Downward Estimate Change [Member] | Large Project Construction [Member]
Change in Accounting Estimate [Line Items]
Number of Projects with Estimate Changes	1	0	2	2
Increase (Decrease) on Project Profitability	(1,600,000)	0	(5,800,000)	(4,700,000)
Downward Estimate Change [Member] | Large Project Construction [Member] | Minimum [Member]
Change in Accounting Estimate [Line Items]
Range Of Effect On Gross Profit	(1,600,000)	0	(2,600,000)	(1,800,000)
Downward Estimate Change [Member] | Large Project Construction [Member] | Maximum [Member]
Change in Accounting Estimate [Line Items]
Range Of Effect On Gross Profit	(1,600,000)	0	(3,200,000)	(2,900,000)
Downward Estimate Change [Member] | Construction [Member]
Change in Accounting Estimate [Line Items]
Number of Projects with Estimate Changes	0	0	0	1
Increase (Decrease) on Project Profitability	0	0	0	(1,600,000)
Downward Estimate Change [Member] | Construction [Member] | Minimum [Member]
Change in Accounting Estimate [Line Items]
Range Of Effect On Gross Profit	0	0	0	(1,600,000)
Downward Estimate Change [Member] | Construction [Member] | Maximum [Member]
Change in Accounting Estimate [Line Items]
Range Of Effect On Gross Profit	0	0	0	(1,600,000)
Construction [Member]
Change in Accounting Estimate [Line Items]
Increase (Decrease) on Project Profitability	$ 1,400,000	$ 0	$ 2,900,000	$ (1,600,000)