Segments Schedule of revenue by geographic region (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	$ 24,878	$ 19,073	$ 47,997	$ 37,396
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	22,019	17,844	42,170	34,270
International
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	$ 2,859	$ 1,229	$ 5,827	$ 3,126