Equity Plan (Details 2) (USD $)	3 Months Ended
	Mar. 31, 2015
Options
Number of Shares
Outstanding at the beginning of the period (in shares)	1,726,106
Exercised (in shares)	(19,234)
Forfeited or expired (in shares)	(55,317)
Outstanding at the end of the period (in shares)	1,651,555
Vested or expected to vest (in shares)	1,568,977
Exercisable at the end of the period (in shares)	1,162,101
Weighted Average Exercise Price
Outstanding at the beginning of the period (in dollars per share)	$ 11.23
Exercised (in dollars per share)	$ 5.52
Forfeited or expired (in dollars per share)	$ 18.16
Outstanding at the end of the period (in dollars per share)	$ 11.06
Weighted Average Remaining Contractual Life
Outstanding at the end of the period	5 years 9 months 18 days
Vested or expected to vest	5 years 9 months 18 days
Exercisable at the end of the period	4 years 7 months 6 days
Aggregate Intrinsic Value
Outstanding at the end of the period (in dollars)	$ 2,668,200
Vested or expected to vest (in dollars)	2,434,790
Exercisable at the end of the period (in dollars)	1,899,289
Unrecognized compensation cost information
Total unrecognized compensation cost related to nonvested stock options granted (in dollars)	1,867,000
Expected weighted-average period for recognition of compensation costs related to nonvested stock options	2 years 6 months 7 days
Restricted stock
Number of Shares
Forfeited or expired (in shares)	(5,000)
Vested or expected to vest (in shares)	(13,750)
Unrecognized compensation cost information
Total unrecognized compensation cost related to nonvested stock options granted (in dollars)	$ 668,000
Expected weighted-average period for recognition of compensation costs related to nonvested stock options	3 years 6 months 18 days
Number of Shares
Nonvested shares at the beginning of the period (in shares)	100,000
Granted (in shares)	5,000
Nonvested shares at the end of the period (in shares)	86,250
Weighted Average Grant Date Fair Value
Nonvested shares at the beginning of the period (in dollars per share)	$ 8.25
Granted (in dollars per share)	$ 8.49
Vested (in dollars per share)	$ 6.98
Forfeited or expired (in dollars per share)	$ 8.70
Nonvested shares at the end of the period (in dollars per share)	$ 8.44