Significant Customers (Details) (Customer Concentration Risk)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Revenues
Concentration Risk
Concentration risk, percentage	17.50%	30.10%
Revenues | Customer A
Concentration Risk
Concentration risk, percentage	17.50%	19.20%
Revenues | Customer B
Concentration Risk
Concentration risk, percentage	0.00%	0.00%
Revenues | Customer C
Concentration Risk
Concentration risk, percentage		10.90%
Gross accounts receivable
Concentration Risk
Concentration risk, percentage	20.30%	39.40%
Gross accounts receivable | Customer A
Concentration Risk
Concentration risk, percentage	20.30%	25.00%
Gross accounts receivable | Customer B
Concentration Risk
Concentration risk, percentage		14.40%