Revisions in Estimates (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Change in Accounting Estimate [Line Items]
Financial Effect on Future Periods	$ 0		$ 0
Amount Considered Significant on Individual Project Gross Profit	1,000,000.0	1,000,000.0	1,000,000.0	1,000,000.0
Construction [Member]
Change in Accounting Estimate [Line Items]
Increase (Decrease) on Project Profitability		(1,600,000)		(800,000)
Contracts Accounted for under Percentage of Completion [Member] | Construction [Member]
Change in Accounting Estimate [Line Items]
Increase (Decrease) on Project Profitability	(500,000)		(300,000)
Contracts Accounted for under Percentage of Completion [Member] | Large Project Construction [Member]
Change in Accounting Estimate [Line Items]
Increase (Decrease) on Project Profitability	8,700,000	9,300,000	17,900,000	13,700,000
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	400,000	400,000	1,400,000	900,000
Upward Estimate Change [Member] | Construction [Member]
Change in Accounting Estimate [Line Items]
Number of Projects with Estimate Changes	1	1	2	3
Increase (Decrease) on Project Profitability	1,600,000	1,400,000	3,100,000	5,400,000
Upward Estimate Change [Member] | Construction [Member] | Minimum [Member]
Change in Accounting Estimate [Line Items]
Range Of Effect On Gross Profit	1,600,000	1,400,000	1,400,000	1,100,000
Upward Estimate Change [Member] | Construction [Member] | Maximum [Member]
Change in Accounting Estimate [Line Items]
Range Of Effect On Gross Profit	1,600,000	1,400,000	1,700,000	3,200,000
Upward Estimate Change [Member] | Large Project Construction [Member]
Change in Accounting Estimate [Line Items]
Number of Projects with Estimate Changes	5	6	5	6
Increase (Decrease) on Project Profitability	15,800,000	14,900,000	31,900,000	23,100,000
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	1,200,000	1,500,000	1,400,000
Upward Estimate Change [Member] | Large Project Construction [Member] | Maximum [Member]
Change in Accounting Estimate [Line Items]
Range Of Effect On Gross Profit	8,300,000	3,600,000	16,100,000	5,200,000
Downward Estimate Change [Member] | Construction [Member]
Change in Accounting Estimate [Line Items]
Number of Projects with Estimate Changes	1	2	2	2
Increase (Decrease) on Project Profitability	(2,100,000)	(3,000,000)	(3,400,000)	(6,200,000)
Downward Estimate Change [Member] | Construction [Member] | Minimum [Member]
Change in Accounting Estimate [Line Items]
Range Of Effect On Gross Profit	(2,100,000)	(1,100,000)	(1,000,000)	(1,400,000)
Downward Estimate Change [Member] | Construction [Member] | Maximum [Member]
Change in Accounting Estimate [Line Items]
Range Of Effect On Gross Profit	(2,100,000)	(1,900,000)	(2,400,000)	(4,800,000)
Downward Estimate Change [Member] | Large Project Construction [Member]
Change in Accounting Estimate [Line Items]
Number of Projects with Estimate Changes	2	1	2	2
Increase (Decrease) on Project Profitability	(7,100,000)	(5,600,000)	(14,000,000)	(9,400,000)
Downward Estimate Change [Member] | Large Project Construction [Member] | Minimum [Member]
Change in Accounting Estimate [Line Items]
Range Of Effect On Gross Profit	(2,800,000)	(5,600,000)	(5,200,000)	(1,500,000)
Downward Estimate Change [Member] | Large Project Construction [Member] | Maximum [Member]
Change in Accounting Estimate [Line Items]
Range Of Effect On Gross Profit	$ (4,300,000)	$ (5,600,000)	$ (8,800,000)	$ (7,900,000)