Revisions in Estimates (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Change in Accounting Estimate [Line Items]
Financial Effect on Future Periods	$ 0
Amount Considered Significant on Individual Project Gross Profit	1.0	1.0	1.0
Adjustment in Revisions in Estimated Total Cost in Excess of Estimated Total Revenue	4.5	10.2
Construction [Member]
Change in Accounting Estimate [Line Items]
Increase (Decrease) on Project Profitability	6.2	3.9	39.1
Contracts Accounted for under Percentage of Completion [Member] | Large Project Construction [Member]
Change in Accounting Estimate [Line Items]
Increase (Decrease) on Project Profitability	8.9	6.0	65.0
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	2.8	2.6	12.3
Upward Estimate Change [Member] | Construction [Member]
Change in Accounting Estimate [Line Items]
Increase (Decrease) on Project Profitability	13.6	12.6	48.9
Number of Projects with Estimate Changes	7	6	22
Upward Estimate Change [Member] | Construction [Member] | Minimum [Member]
Change in Accounting Estimate [Line Items]
Range Of Effect On Gross Profit	1.0	1.0	1.0
Upward Estimate Change [Member] | Construction [Member] | Maximum [Member]
Change in Accounting Estimate [Line Items]
Range Of Effect On Gross Profit	3.5	4.2	7.0
Upward Estimate Change [Member] | Large Project Construction [Member]
Change in Accounting Estimate [Line Items]
Increase (Decrease) on Project Profitability	28.3	18.0	68.4
Number of Projects with Estimate Changes	9	6	14
Litigation Settlement, Gross			17.3
Upward Estimate Change [Member] | Large Project Construction [Member] | Minimum [Member]
Change in Accounting Estimate [Line Items]
Range Of Effect On Gross Profit	1.1	1.1	1.0
Upward Estimate Change [Member] | Large Project Construction [Member] | Maximum [Member]
Change in Accounting Estimate [Line Items]
Range Of Effect On Gross Profit	6.9	4.8	19.8
Downward Estimate Change [Member] | Construction [Member]
Change in Accounting Estimate [Line Items]
Increase (Decrease) on Project Profitability	(7.4)	(8.7)	(9.8)
Number of Projects with Estimate Changes	4	5	2
Downward Estimate Change [Member] | Construction [Member] | Minimum [Member]
Change in Accounting Estimate [Line Items]
Range Of Effect On Gross Profit	(1.4)	(1.1)	(2.4)
Downward Estimate Change [Member] | Construction [Member] | Maximum [Member]
Change in Accounting Estimate [Line Items]
Range Of Effect On Gross Profit	(2.6)	(2.5)	(7.4)
Downward Estimate Change [Member] | Large Project Construction [Member]
Change in Accounting Estimate [Line Items]
Increase (Decrease) on Project Profitability	(19.4)	(12.0)	(3.4)
Number of Projects with Estimate Changes	5	2	2
Downward Estimate Change [Member] | Large Project Construction [Member] | Minimum [Member]
Change in Accounting Estimate [Line Items]
Range Of Effect On Gross Profit	(1.2)	(1.8)	(1.3)
Downward Estimate Change [Member] | Large Project Construction [Member] | Maximum [Member]
Change in Accounting Estimate [Line Items]
Range Of Effect On Gross Profit	$ (5.1)	$ (10.2)	$ (2.1)
Complete or Substantially Complete [Member] | Downward Estimate Change [Member] | Construction [Member]
Change in Accounting Estimate [Line Items]
Number of Projects with Estimate Changes	2
Not, Complete or Substantially Complete [Member] | Downward Estimate Change [Member] | Construction [Member]
Change in Accounting Estimate [Line Items]
Number of Projects with Estimate Changes	2
Contract 1, that was not complete or substantially complete [Member] | Not, Complete or Substantially Complete [Member] | Downward Estimate Change [Member] | Construction [Member]
Change in Accounting Estimate [Line Items]
Percent Complete	49.20%
Contract 2, that was not complete or substantially complete [Member] | Not, Complete or Substantially Complete [Member] | Downward Estimate Change [Member] | Construction [Member]
Change in Accounting Estimate [Line Items]
Percent Complete	70.50%