Revisions in Estimates (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 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		(6,000,000)		(9,400,000)
Contracts Accounted for under Percentage of Completion [Member] | Construction [Member]
Change in Accounting Estimate [Line Items]
Increase (Decrease) on Project Profitability	(1,500,000)		(600,000)
Contracts Accounted for under Percentage of Completion [Member] | Large Project Construction [Member]
Change in Accounting Estimate [Line Items]
Increase (Decrease) on Project Profitability	6,800,000	35,900,000	13,600,000	48,900,000
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	5,900,000	5,700,000	4,300,000	6,600,000
Upward Estimate Change [Member] | Construction [Member]
Change in Accounting Estimate [Line Items]
Number of Projects with Estimate Changes	4	1	5	4
Increase (Decrease) on Project Profitability	7,400,000	1,600,000	11,800,000	7,100,000
Upward Estimate Change [Member] | Construction [Member] | Minimum [Member]
Change in Accounting Estimate [Line Items]
Range Of Effect On Gross Profit	1,300,000	1,600,000	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	2,700,000	1,600,000	3,000,000	3,000,000
Upward Estimate Change [Member] | Large Project Construction [Member]
Change in Accounting Estimate [Line Items]
Number of Projects with Estimate Changes	3	8	6	8
Increase (Decrease) on Project Profitability	12,900,000	35,900,000	47,500,000	54,700,000
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	1,100,000	2,100,000	1,100,000
Upward Estimate Change [Member] | Large Project Construction [Member] | Maximum [Member]
Change in Accounting Estimate [Line Items]
Range Of Effect On Gross Profit	10,500,000	12,600,000	26,600,000	16,300,000
Downward Estimate Change [Member] | Construction [Member]
Change in Accounting Estimate [Line Items]
Number of Projects with Estimate Changes	3	4	4	6
Increase (Decrease) on Project Profitability	(5,900,000)	(7,600,000)	(11,200,000)	(16,500,000)
Downward Estimate Change [Member] | Construction [Member] | Minimum [Member]
Change in Accounting Estimate [Line Items]
Range Of Effect On Gross Profit	(1,500,000)	(1,100,000)	(1,100,000)	(1,100,000)
Downward Estimate Change [Member] | Construction [Member] | Maximum [Member]
Change in Accounting Estimate [Line Items]
Range Of Effect On Gross Profit	(2,500,000)	(3,900,000)	(4,300,000)	(6,300,000)
Downward Estimate Change [Member] | Large Project Construction [Member]
Change in Accounting Estimate [Line Items]
Number of Projects with Estimate Changes	4	0	4	2
Increase (Decrease) on Project Profitability	(19,700,000)	0	(33,900,000)	(5,800,000)
Downward Estimate Change [Member] | Large Project Construction [Member] | Minimum [Member]
Change in Accounting Estimate [Line Items]
Range Of Effect On Gross Profit	(1,400,000)	0	(1,600,000)	(1,700,000)
Downward Estimate Change [Member] | Large Project Construction [Member] | Maximum [Member]
Change in Accounting Estimate [Line Items]
Range Of Effect On Gross Profit	$ (14,700,000)	$ 0	$ (23,500,000)	$ (4,100,000)