Summary Of Significant Accounting Policies (Schedule Of Percentage Of Company's Total Revenues) (Details)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Georgia [Member]
Percentage of revenues under contracts or subcontracts	13.00%	17.00%	19.00%
Ohio [Member]
Percentage of revenues under contracts or subcontracts	10.00%	13.00%	14.00%
Texas [Member]
Percentage of revenues under contracts or subcontracts	26.00%	30.00%	30.00%