Segment Information (Narrative) (Details)	12 Months Ended
	Dec. 31, 2012 segment	Dec. 31, 2012 Sales Revenue, Services, Net [Member] Customer1 [Member] Customer Concentration Risk [Member]	Dec. 31, 2011 Sales Revenue, Services, Net [Member] Customer1 [Member] Customer Concentration Risk [Member]	Dec. 31, 2010 Sales Revenue, Services, Net [Member] Customer1 [Member] Customer Concentration Risk [Member]	Dec. 31, 2011 Sales Revenue, Services, Net [Member] Customer2 [Member] Customer Concentration Risk [Member]	Dec. 31, 2010 Sales Revenue, Services, Net [Member] Customer2 [Member] Customer Concentration Risk [Member]
Segment Reporting Information [Line Items]
Number of Reportable Segments	2
Concentration Risk, Percentage		11.00%	10.00%	11.00%	12.00%	12.00%