Revisions in Estimates (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Change in Accounting Estimate [Line Items]
Amount Considered Significant to Individual Project Gross Profit	$ 24,500,000	$ 8,700,000	$ 28,600,000	$ 15,200,000
Financial Effect on Future Periods	0		0
Construction [Member]
Change in Accounting Estimate [Line Items]
Amount Considered Significant to Individual Project Gross Profit	1,000,000
Increase (Decrease) on Project Profitability	1,400,000	500,000	8,300,000	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	25,700,000	8,700,000	34,500,000	17,900,000
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	8,200,000	400,000	7,500,000	1,400,000
Upward Estimate Change [Member] | Construction [Member]
Change in Accounting Estimate [Line Items]
Number of Projects with Estimate Changes	0	1	0	2
Range Of Effect On Gross Profit	0	(1,600,000)	0
Increase (Decrease) on Project Profitability	0	1,600,000	0	3,100,000
Upward Estimate Change [Member] | Construction [Member] | Minimum [Member]
Change in Accounting Estimate [Line Items]
Range Of Effect On Gross Profit				(1,400,000)
Upward Estimate Change [Member] | Construction [Member] | Maximum [Member]
Change in Accounting Estimate [Line Items]
Range Of Effect On Gross Profit				(1,700,000)
Upward Estimate Change [Member] | Large Project Construction [Member]
Change in Accounting Estimate [Line Items]
Number of Projects with Estimate Changes	6	5	9	5
Increase (Decrease) on Project Profitability	28,000,000	15,800,000	41,300,000	31,900,000
Upward Estimate Change [Member] | Large Project Construction [Member] | Minimum [Member]
Change in Accounting Estimate [Line Items]
Range Of Effect On Gross Profit	(1,100,000)	(1,300,000)	(1,100,000)	(1,500,000)
Upward Estimate Change [Member] | Large Project Construction [Member] | Maximum [Member]
Change in Accounting Estimate [Line Items]
Range Of Effect On Gross Profit	(19,700,000)	(8,300,000)	(16,300,000)	(16,100,000)
Downward Estimate Change [Member] | Construction [Member]
Change in Accounting Estimate [Line Items]
Number of Projects with Estimate Changes	1	1	5	2
Range Of Effect On Gross Profit	(1,400,000)	(2,100,000)
Increase (Decrease) on Project Profitability	1,400,000	2,100,000	8,300,000	3,400,000
Downward Estimate Change [Member] | Construction [Member] | Minimum [Member]
Change in Accounting Estimate [Line Items]
Range Of Effect On Gross Profit			1,100,000	1,000,000
Downward Estimate Change [Member] | Construction [Member] | Maximum [Member]
Change in Accounting Estimate [Line Items]
Range Of Effect On Gross Profit			2,200,000	2,400,000
Downward Estimate Change [Member] | Large Project Construction [Member]
Change in Accounting Estimate [Line Items]
Number of Projects with Estimate Changes	1	2	1	2
Range Of Effect On Gross Profit	(2,300,000)		(6,800,000)
Increase (Decrease) on Project Profitability	(2,300,000)	(7,100,000)	(6,800,000)	(14,000,000)
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		5,200,000
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		$ 8,800,000