Concentration Risk (Narrative) (Details)	3 Months Ended	12 Months Ended
	Mar. 31, 2012	Dec. 31, 2011
Customer One [Member]
Concentration Risk [Line Items]
Percentage of accounts receivable from one customer out of total accounts receivable	22.00%	23.00%
Customer Two [Member]
Concentration Risk [Line Items]
Percentage of accounts receivable from one customer out of total accounts receivable	12.00%	11.00%
Customer Concentration Risk [Member]
Concentration Risk [Line Items]
Percentage of revenue from one customer out of total revenue		19.00%