Concentrations of Credit and Other Risks (Details)	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration of share of accounts receivable, maximum (in hundredths)	10.00%	10.00%
Concentration of revenue share, maximum (in hundredths)	10.00%	10.00%
United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk, percentage (in hundredths)	84.00%	84.00%
International Markets [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk, percentage (in hundredths)	16.00%	16.00%