Disposition Of Assets (Components Of The Results Of Discontinued Operations For The UK Construction Operations) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Statement [Abstract]
Loss from discontinued operation, net of income taxes									$ (4,690)	$ (23,069)	$ (7,804)
Diluted loss per share from discontinued operation (in US dollars per share)	$ (0.01)	$ (0.01)	$ (0.02)	$ (0.03)	$ (0.08)	$ (0.04)	$ (0.16)	$ (0.06)	$ (0.07)	$ (0.34)	$ (0.12)
Restructuring reserve	281				194				281	194	53
United Kingdom Construction
Income Statement [Abstract]
Revenues									19,297	83,631	151,185
Loss from discontinued operation, net of income taxes									(4,690)	(23,069)	(7,804)
Diluted loss per share from discontinued operation (in US dollars per share)									$ (0.07)	$ (0.34)	$ (0.12)
Restructuring reserve	1,700								1,700
Assets of discontinued operation:
Current assets	6,265				26,630				6,265	26,630
Non-current assets	278				833				278	833
Liabilities of discontinued operation:
Current liabilities	10,743				41,024				10,743	41,024
Non-current liabilities	$ 94				$ 513				$ 94	$ 513