Geographic Information (Details) (USD $)
In Thousands, unless otherwise specified
3 Months Ended 12 Months Ended
Dec. 31, 2011
Sep. 30, 2011
Jun. 30, 2011
Mar. 31, 2011
Dec. 31, 2010
Sep. 30, 2010
Jun. 30, 2010
Mar. 31, 2010
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2009
Revenue and long-lived assets by geographical segments                      
Revenues $ 108,301 $ 84,594 $ 67,852 $ 63,510 $ 75,181 $ 55,626 $ 58,190 $ 52,331 $ 324,257 $ 241,328 $ 182,713
North America
                     
Revenue and long-lived assets by geographical segments                      
Revenues                 281,092 236,959 180,127
Europe, Middle East and Africa
                     
Revenue and long-lived assets by geographical segments                      
Revenues                 30,645 3,770 2,010
Asia Pacific
                     
Revenue and long-lived assets by geographical segments                      
Revenues                 9,144 434 375
Latin America
                     
Revenue and long-lived assets by geographical segments                      
Revenues                 $ 3,376 $ 165 $ 201
Foreign Jurisdictions
                     
Revenue and long-lived assets by geographical segments                      
Percentage of revenue or about the percentage of revenue                 0.13