Stock Option Activity (Details) (Stock Options, USD $) In Thousands, except Share data, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
Stock Options
Number of Options (in shares):
Beginning balance	3,287,207
Options granted	972,734
Options exercised	(246,456)
Options canceled	(353,454)
Ending balance	3,660,031	3,287,207
Weighted Average Exercise Price (in dollars per share):
Beginning balance	$ 9.62
Options granted	$ 11.85
Options exercised	$ 3.55
Options canceled	$ 14.25
Ending balance	$ 10.17	$ 9.62
Wtd avg remaining term, Outstanding	6 years 2 months 12 days	6 years 5 months 12 days
Aggregate intrinsic value, Outstanding	$ 8,265	$ 24,880