Equity Plan (Details 2) (2004 Plan, USD $)	6 Months Ended
	Jun. 30, 2013
Options
Number of Shares
Outstanding at the beginning of the period (in shares)	1,314,347
Granted (in shares)	272,050
Exercised (in shares)	(6,374)
Forfeited or expired (in shares)	(29,885)
Outstanding at the end of the period (in shares)	1,550,138
Vested or expected to vest (in shares)	1,472,631
Exercisable at the end of the period (in shares)	1,033,651
Weighted Average Exercise Price
Outstanding at the beginning of the period (in dollars per share)	$ 12.90
Granted (in dollars per share)	$ 6.57
Exercised (in dollars per share)	$ 4.09
Forfeited or expired (in dollars per share)	$ 11.49
Outstanding at the end of the period (in dollars per share)	$ 11.85
Weighted Average Remaining Contractual Life (Years)
Outstanding at the end of the period	6 years 1 month 6 days
Vested or expected to vest	6 years 1 month 6 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)	$ 1,030,000
Vested or expected to vest (in dollars)	978,000
Exercisable at the end of the period (in dollars)	592,000
Unrecognized compensation cost information
Total unrecognized compensation cost related to nonvested stock options granted (in dollars)	1,914,000
Expected weighted-average period for recognition of compensation costs related to nonvested stock options	3 years 2 months 19 days
Restricted stock
Unrecognized compensation cost information
Total unrecognized compensation cost related to nonvested stock options granted (in dollars)	$ 198,000
Expected weighted-average period for recognition of compensation costs related to nonvested stock options	1 year 1 month 6 days
Number of Shares
Nonvested shares at the beginning of the period (in shares)	88,000
Granted (in shares)	10,000
Vested (in shares)	(40,000)
Nonvested shares at the end of the period (in shares)	58,000
Weighted Average Grant Date Fair Value
Nonvested shares at the beginning of the period (in dollars per share)	$ 5.74
Granted (in dollars per share)	$ 6.51
Vested (in dollars per share)	$ 5.16
Nonvested shares at the end of the period (in dollars per share)	$ 6.28