Stock-based Compensation, Option Plans and Warrants (Details) (USD $) | 12 Months Ended | 0 Months Ended | 1 Months Ended | 12 Months Ended |
Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012 | Mar. 12, 2015 | Apr. 30, 2012 | Mar. 31, 2012 |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | | | | | | |
Stock-based compensation expense | $2,703,000 | $2,114,000 | $2,091,000 | | | |
Director Stock Awards [Abstract] | | | | | | |
Shares reserved for issuance (in shares) | 7,317,368 | | | | | |
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items] | | | | | | |
Options outstanding, Number (in shares) | 5,885,470 | | | | | |
Exercisable, Number (in shares) | 4,111,853 | | | | | |
$0.99 - 1.99 | | | | | | |
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items] | | | | | | |
Stock option plans exercise price range, lower range limit (in dollars per share) | $1 | | | | | |
Stock option plans exercise price range, upper limit (in dollars per share) | $1.99 | | | | | |
Options outstanding, Number (in shares) | 1,679,079 | | | | | |
Options outstanding, Weighted average remaining life | 4 years 11 months 1 day | | | | | |
Options outstanding, Weighted average exercise price (in dollars per share) | $1.49 | | | | | |
Exercisable, Number (in shares) | 1,579,079 | | | | | |
Exercisable, Weighted average remaining life | 4 years 8 months 27 days | | | | | |
Exercisable, Weighted average exercise price (in dollars per share) | $1.45 | | | | | |
$2.00 - 2.99 | | | | | | |
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items] | | | | | | |
Stock option plans exercise price range, lower range limit (in dollars per share) | $2 | | | | | |
Stock option plans exercise price range, upper limit (in dollars per share) | $2.99 | | | | | |
Options outstanding, Number (in shares) | 1,414,200 | | | | | |
Options outstanding, Weighted average remaining life | 6 years 9 months 18 days | | | | | |
Options outstanding, Weighted average exercise price (in dollars per share) | $2.34 | | | | | |
Exercisable, Number (in shares) | 940,077 | | | | | |
Exercisable, Weighted average remaining life | 6 years | | | | | |
Exercisable, Weighted average exercise price (in dollars per share) | $2.31 | | | | | |
$3.00 - 3.99 | | | | | | |
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items] | | | | | | |
Stock option plans exercise price range, lower range limit (in dollars per share) | $3 | | | | | |
Stock option plans exercise price range, upper limit (in dollars per share) | $3.99 | | | | | |
Options outstanding, Number (in shares) | 1,509,441 | | | | | |
Options outstanding, Weighted average remaining life | 7 years 9 months 22 days | | | | | |
Options outstanding, Weighted average exercise price (in dollars per share) | $3.36 | | | | | |
Exercisable, Number (in shares) | 437,322 | | | | | |
Exercisable, Weighted average remaining life | 5 years 2 months 19 days | | | | | |
Exercisable, Weighted average exercise price (in dollars per share) | $3.63 | | | | | |
$4.00 - 4.99 | | | | | | |
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items] | | | | | | |
Stock option plans exercise price range, lower range limit (in dollars per share) | $4 | | | | | |
Stock option plans exercise price range, upper limit (in dollars per share) | $4.99 | | | | | |
Options outstanding, Number (in shares) | 1,109,750 | | | | | |
Options outstanding, Weighted average remaining life | 3 years 6 months 18 days | | | | | |
Options outstanding, Weighted average exercise price (in dollars per share) | $4.58 | | | | | |
Exercisable, Number (in shares) | 987,375 | | | | | |
Exercisable, Weighted average remaining life | 3 years 1 month 21 days | | | | | |
Exercisable, Weighted average exercise price (in dollars per share) | $4.57 | | | | | |
$5.00 - 5.99 | | | | | | |
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items] | | | | | | |
Stock option plans exercise price range, lower range limit (in dollars per share) | $5 | | | | | |
Stock option plans exercise price range, upper limit (in dollars per share) | $5.99 | | | | | |
Options outstanding, Number (in shares) | 100,000 | | | | | |
Options outstanding, Weighted average remaining life | 9 years 4 months 6 days | | | | | |
Options outstanding, Weighted average exercise price (in dollars per share) | $5.39 | | | | | |
Exercisable, Number (in shares) | 96,000 | | | | | |
Exercisable, Weighted average remaining life | 9 years 4 months 6 days | | | | | |
Exercisable, Weighted average exercise price (in dollars per share) | $5.38 | | | | | |
$6.00 - 6.28 | | | | | | |
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items] | | | | | | |
Stock option plans exercise price range, lower range limit (in dollars per share) | $6 | | | | | |
Stock option plans exercise price range, upper limit (in dollars per share) | $6.28 | | | | | |
Options outstanding, Number (in shares) | 73,000 | | | | | |
Options outstanding, Weighted average remaining life | 1 year 3 months 4 days | | | | | |
Options outstanding, Weighted average exercise price (in dollars per share) | $6.05 | | | | | |
Exercisable, Number (in shares) | 72,000 | | | | | |
Exercisable, Weighted average remaining life | 1 year 1 month 24 days | | | | | |
Exercisable, Weighted average exercise price (in dollars per share) | $6.05 | | | | | |
Stock Options [Member] | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | | | | | | |
Stock-based compensation expense | 1,820,000 | 1,700,000 | 1,600,000 | | | |
Weighted average assumptions used in fair value of the options [Abstract] | | | | | | |
Weighted average value per option granted during the period (in dollars per share) | $2.44 | $1.73 | $2.17 | | | |
Assumptions [Abstract] | | | | | | |
Expected dividend yield (in hundredths) | 0.00% | 0.00% | 0.00% | | | |
Volatility (in hundredths) | 80.70% | 81.20% | 81.40% | | | |
Risk free interest rate (in hundredths) | 2.05% | 1.24% | 1.19% | | | |
Expected life (years) | 6 years 7 months 6 days | 6 years 6 months | 6 years 8 months 12 days | | | |
Fair value of options granted | 2,666,000 | 1,444,000 | 1,324,000 | | | |
Authorized shares available for grant (in shares) | 5,200,000 | | | | | |
Options expiration period | 10 years | | | | | |
Options [Roll Forward] | | | | | | |
Options outstanding, beginning balance (in shares) | 5,400,000 | 4,761,000 | 4,756,000 | | | |
Granted (in shares) | 1,091,000 | 836,000 | 610,000 | | | |
Exercised (in shares) | -410,000 | -166,000 | -391,000 | | | |
Forfeited/Expired (in shares) | -196,000 | -31,000 | -214,000 | | | |
Options outstanding, ending balance (in shares) | 5,885,000 | 5,400,000 | 4,761,000 | | | |
Exercisable at end of year (in shares) | 4,112,000 | | | | | |
Weighted average exercise price [Roll Forward] | | | | | | |
Options outstanding, beginning balance (in dollars per share) | $2.77 | $2.77 | $2.61 | | | |
Granted (in dollars per share) | $3.38 | $2.43 | $3.01 | | | |
Exercised (in dollars per share) | $2.71 | $1.18 | $1.11 | | | |
Forfeited/Expired (in dollars per share) | $3.08 | $2.58 | $2.80 | | | |
Options outstanding, ending balance (in dollars per share) | $2.88 | $2.77 | $2.77 | | | |
Options outstanding weighted average exercise price of options exercisable | | | | | | |
Weighted average remaining life [Abstract] | | | | | | |
Options outstanding ending balance | 5 years 10 months 24 days | | | | | |
Exercisable at end of year | 4 years 8 months 12 days | | | | | |
Fair value per share [Abstract] | | | | | | |
Options outstanding, ending balance (in dollars per share) | $2.06 | | | | | |
Exercisable at end of year, Fair value (in dollars per share) | $2.02 | | | | | |
Other information pertaining to stock options activity [Abstract] | | | | | | |
Weighted average grant date fair value of stock options granted (in dollars per share) | $2.44 | $1.73 | $2.17 | | | |
Total fair value of options vested | 1,718,000 | 1,670,000 | 1,497,000 | | | |
Total intrinsic value of options exercised | 932,000 | 275,000 | 414,000 | | | |
Compensation cost related to non-vested awards not yet recognized | 2,590,000 | | | | | |
Restricted Unit Awards [Member] | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | | | | | | |
Stock-based compensation expense | 883,000 | 400,000 | 500,000 | | | |
Restricted Stock Awards [Abstract] | | | | | | |
Compensation cost not yet recognized | 4,651,000 | | | | | |
Number of Shares [Roll Forward] | | | | | | |
Unvested, Beginning balance (in shares) | 355,240 | 482,025 | 629,771 | | | |
Granted (in shares) | 1,582,000 | 48,222 | 89,860 | | | |
Vested/Released (in shares) | -121,622 | -169,700 | -229,172 | | | |
Forfeited (in shares) | -39,528 | -5,307 | -8,434 | | | |
Unvested, Ending balance (in shares) | 1,776,090 | 355,240 | 482,025 | | | |
Weighted average grant date fair value [Roll Forward] | | | | | | |
Unvested, beginning balance (in dollars per share) | $3.24 | $3.09 | $3.03 | | | |
Granted (in dollars per share) | $3.49 | $2.69 | $2.12 | | | |
Vested/Released (in dollars per share) | $3.64 | $2.66 | $2.57 | | | |
Forfeited (in dollars per share) | $3.44 | $3.08 | $2.42 | | | |
Unvested, Ending balance (in dollars per share) | $3.43 | $3.24 | $3.09 | | | |
2005 Directors Plan [Member] | | | | | | |
Director Stock Awards [Abstract] | | | | | | |
Shares reserved for issuance (in shares) | 1,500,000 | | | | | |
Number of shares to be granted for participation in board and committee meetings as per agreement (in shares) | 12,000 | | | 25,000 | | |
Maximum shares that can be awarded to one person (in shares) | 100,000 | | | | | |
Percentage of exercise price awarded (in hundredths) | 100.00% | | | | | |
Annual retainer fee | | | | | $40,000 | $27,500 |