Stock-Based Compensation (Details 3) (USD $)	12 Months Ended
	Dec. 31, 2012
Options outstanding
Number of Options (in shares)	2,788,599
Weighted average remaining contractual term	7 years 11 months 19 days
Options exercisable
Number of Options (in shares)	1,450,461
Weighted average remaining contractual term	6 years 9 months 29 days
$0.80 - $2.11
Stock options outstanding
Exercise price, low end of range (in dollars per share)	0.80
Exercise price, high end of range (in dollars per share)	2.11
Options outstanding
Number of Options (in shares)	955,490
Weighted average remaining contractual term	5 years 10 months 6 days
Options exercisable
Number of Options (in shares)	930,007
Weighted average remaining contractual term	5 years 9 months 7 days
$2.12 - $3.42
Stock options outstanding
Exercise price, low end of range (in dollars per share)	2.12
Exercise price, high end of range (in dollars per share)	3.42
Options outstanding
Number of Options (in shares)	648,866
Weighted average remaining contractual term	9 years 2 months 16 days
Options exercisable
Number of Options (in shares)	71,303
Weighted average remaining contractual term	9 years 1 month 6 days
$3.43 - $4.74
Stock options outstanding
Exercise price, low end of range (in dollars per share)	3.43
Exercise price, high end of range (in dollars per share)	4.74
Options outstanding
Number of Options (in shares)	803,399
Weighted average remaining contractual term	9 years 6 months 22 days
Options exercisable
Number of Options (in shares)	212,847
Weighted average remaining contractual term	9 years 6 months 14 days
$4.75 - $6.06
Stock options outstanding
Exercise price, low end of range (in dollars per share)	4.75
Exercise price, high end of range (in dollars per share)	6.06
Options outstanding
Number of Options (in shares)	80,000
Weighted average remaining contractual term	7 years 9 months 25 days
Options exercisable
Number of Options (in shares)	39,063
Weighted average remaining contractual term	7 years 9 months 18 days
$6.07 - $7.37
Stock options outstanding
Exercise price, low end of range (in dollars per share)	6.07
Exercise price, high end of range (in dollars per share)	7.37
Options outstanding
Number of Options (in shares)	10,683
Weighted average remaining contractual term	8 years 6 months
Options exercisable
Number of Options (in shares)	10,339
Weighted average remaining contractual term	8 years 5 months 26 days
$7.38 - $8.69
Stock options outstanding
Exercise price, low end of range (in dollars per share)	7.38
Exercise price, high end of range (in dollars per share)	8.69
Options outstanding
Number of Options (in shares)	121,104
Weighted average remaining contractual term	8 years 1 month 6 days
Options exercisable
Number of Options (in shares)	86,816
Weighted average remaining contractual term	8 years 2 months 1 day
$8.70 - $10.00
Stock options outstanding
Exercise price, low end of range (in dollars per share)	8.70
Exercise price, high end of range (in dollars per share)	10.00
Options outstanding
Number of Options (in shares)	169,057
Weighted average remaining contractual term	7 years 7 months 10 days
Options exercisable
Number of Options (in shares)	100,086
Weighted average remaining contractual term	7 years 7 months 10 days