Disposition Of Assets (Components Of The Results Of Discontinued Operations For The Canada Construction Segment) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended			7 Months Ended		12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Aug. 02, 2011 Canada Construction		Dec. 31, 2011 Canada Construction	Dec. 31, 2010 Canada Construction
Income Statement [Abstract]
Revenues												$ 118,214	[1]		$ 269,332
Loss from discontinued operation (net of income taxes)												(44)	[1]		(849)
Gain on sale of discontinued operation (net of income taxes)									0	9,127	0	9,127	[1]	9,100	0
Net income (loss) from discontinued operation									0	9,083	(849)	9,083	[1]		(849)
Diluted earnings (loss) per share from discontinued operation	$ 0.00	$ 0.00	$ 0.00	$ 0.00	$ 0.01	$ 0.13	$ (0.01)	$ 0.01	$ 0.00	$ 0.13	$ (0.01)	$ 0.13	[1]		$ (0.01)
Assets of discontinued operation:
Current assets															99,173
Non-current assets															3,827
Liabilities of discontinued operation:
Current liabilities															53,853
Non-current liabilities															$ 4,108

[1] Through the date of sale, August 2, 2011.