Equity Incentive Plans and Stock-Based Compensation (Details 4)	12 Months Ended
	Dec. 31, 2017 $ / shares shares
Exercise price range 1
Exercise price range
Exercise price range, low end of range (in dollars per share)	$ 4.13
Exercise price range, high end of range (in dollars per share)	$ 5.39
Options Outstanding
Number Outstanding (in shares) | shares	75,665
Weighted Average Remaining Contractual Life (in years)	4 years 8 months 8 days
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 4.60
Options Exercisable
Number Exercisable (in shares) | shares	75,665
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 4.60
Exercise price range 2
Exercise price range
Exercise price range, low end of range (in dollars per share)	5.46
Exercise price range, high end of range (in dollars per share)	$ 5.46
Options Outstanding
Number Outstanding (in shares) | shares	447,780
Weighted Average Remaining Contractual Life (in years)	5 years 29 days
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 5.46
Options Exercisable
Number Exercisable (in shares) | shares	447,780
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 5.46
Exercise price range 3
Exercise price range
Exercise price range, low end of range (in dollars per share)	5.49
Exercise price range, high end of range (in dollars per share)	$ 5.63
Options Outstanding
Number Outstanding (in shares) | shares	237,068
Weighted Average Remaining Contractual Life (in years)	2 years 5 months 5 days
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 5.63
Options Exercisable
Number Exercisable (in shares) | shares	237,068
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 5.63
Exercise price range 4
Exercise price range
Exercise price range, low end of range (in dollars per share)	5.76
Exercise price range, high end of range (in dollars per share)	$ 5.76
Options Outstanding
Number Outstanding (in shares) | shares	596,669
Weighted Average Remaining Contractual Life (in years)	4 years 6 months
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 5.76
Options Exercisable
Number Exercisable (in shares) | shares	596,669
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 5.76
Exercise price range 5
Exercise price range
Exercise price range, low end of range (in dollars per share)	6.83
Exercise price range, high end of range (in dollars per share)	$ 8.73
Options Outstanding
Number Outstanding (in shares) | shares	407,628
Weighted Average Remaining Contractual Life (in years)	3 years 3 months 14 days
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 7.77
Options Exercisable
Number Exercisable (in shares) | shares	407,628
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 7.77
Exercise price range 6
Exercise price range
Exercise price range, low end of range (in dollars per share)	8.76
Exercise price range, high end of range (in dollars per share)	$ 8.76
Options Outstanding
Number Outstanding (in shares) | shares	674,798
Weighted Average Remaining Contractual Life (in years)	6 years 22 days
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 8.76
Options Exercisable
Number Exercisable (in shares) | shares	635,447
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 8.76
Exercise price range 7
Exercise price range
Exercise price range, low end of range (in dollars per share)	9.18
Exercise price range, high end of range (in dollars per share)	$ 11.92
Options Outstanding
Number Outstanding (in shares) | shares	433,979
Weighted Average Remaining Contractual Life (in years)	6 years 5 months 12 days
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 11.21
Options Exercisable
Number Exercisable (in shares) | shares	323,859
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 11.17
Exercise price range 8
Exercise price range
Exercise price range, low end of range (in dollars per share)	11.93
Exercise price range, high end of range (in dollars per share)	$ 12.31
Options Outstanding
Number Outstanding (in shares) | shares	498,356
Weighted Average Remaining Contractual Life (in years)	8 years 1 month 10 days
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 12.26
Options Exercisable
Number Exercisable (in shares) | shares	201,321
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 12.28
Exercise price range 9
Exercise price range
Exercise price range, low end of range (in dollars per share)	12.33
Exercise price range, high end of range (in dollars per share)	$ 12.33
Options Outstanding
Number Outstanding (in shares) | shares	1,478
Weighted Average Remaining Contractual Life (in years)	1 month 17 days
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 12.33
Options Exercisable
Number Exercisable (in shares) | shares	1,478
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 12.33
Exercise price range 10
Exercise price range
Exercise price range, low end of range (in dollars per share)	12.80
Exercise price range, high end of range (in dollars per share)	$ 23.60
Options Outstanding
Number Outstanding (in shares) | shares	936,940
Weighted Average Remaining Contractual Life (in years)	5 years 11 months 12 days
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 15.50
Options Exercisable
Number Exercisable (in shares) | shares	501,680
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 17.60
Exercise price range 11
Exercise price range
Exercise price range, low end of range (in dollars per share)	4.13
Exercise price range, high end of range (in dollars per share)	$ 23.60
Options Outstanding
Number Outstanding (in shares) | shares	4,310,361
Weighted Average Remaining Contractual Life (in years)	5 years 6 months 4 days
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 9.78
Options Exercisable
Number Exercisable (in shares) | shares	3,428,595
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 9.11