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)	$ 1.00
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)	$ 2.00
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)	$ 3.00
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)	$ 4.00
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)	$ 5.00
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)	$ 6.00
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)	5,200,000.0
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