Stockholders' Equity, Equity Incentive Plans and Warrants (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended	12 Months Ended				12 Months Ended		12 Months Ended			12 Months Ended	0 Months Ended	12 Months Ended									12 Months Ended
	Dec. 31, 2013	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Jan. 31, 2008	Dec. 31, 2013 2000 EIP [Member]	Jun. 15, 2009 2000 EIP [Member]	Dec. 31, 2013 2009 EIP [Member]	May 02, 2011 2009 EIP [Member]	Jun. 15, 2009 2009 EIP [Member]	Dec. 31, 2013 2000 NEDSOP [Member]	Jun. 15, 2009 2000ESPP [Member]	Dec. 31, 2013 2000ESPP [Member]	Dec. 31, 2012 2000ESPP [Member]	Dec. 31, 2011 2000ESPP [Member]	Dec. 31, 2013 Restricted Stock [Member]	Dec. 31, 2012 Restricted Stock [Member]	Dec. 31, 2011 Restricted Stock [Member]	Dec. 31, 2013 Restricted Stock [Member] 2000 EIP [Member]	Dec. 31, 2013 Restricted Stock [Member] 2009 EIP [Member]	Dec. 31, 2013 Performance Shares [Member] 2009 EIP [Member]	Dec. 31, 2013 Director [Member] 2000 NEDSOP [Member]	Dec. 31, 2013 Director [Member] Vesting after first year [Member] 2000 NEDSOP [Member]	Dec. 31, 2013 Common Stock [Member]	Dec. 31, 2012 Common Stock [Member]	Dec. 31, 2011 Common Stock [Member]	Dec. 31, 2010 Common Stock [Member]	Jan. 31, 2008 Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected Term						10 years		7 years					6 months	6 months	6 months
Common stock reserved for future issuance (in shares)							7,112,217	2,684,232	8,000,000	4,500,000
Common stock, shares outstanding	59,138,000	59,138,000	58,265,000																0	92,811	0			59,138,000	58,265,000	57,699,000	55,953,000
Options to purchase common stock, outstanding	9,850,498	9,850,498	8,952,129			3,174,089		6,076,409					1,058,720				655,402					600,000
Percentage of awards vesting																						25.00%
Share-based Goods and Nonemployee Services Transaction, Valuation Method, Expected Term											10 years
Award vesting period																						4 years	1 year
Deferred Compensation Arrangement with Individual, Common Stock Reserved for Future Issuance																						1,000,000
Number of shares available for grant																						293,124
Stock Issued During Period, Shares, New Issues												4,000,000
Discount from market price on share purchases													85.00%
Shares issued in period													808,761	675,149
Total unrecognized share-based compensation cost	$ 3.4	$ 3.4
Unrecognized compensation cost, period for recognition													2 years 6 months
Options granted, weighted average exercise price		$ 1.05	$ 0.89	$ 1.78												$ 1.74
Options outstanding, weighted average exercise price																$ 1.74	$ 1.23	$ 2.68
Intrinsic value of options exercised		0.2	0	0.8
Fair value of options vested in period	2.2		2.1	1.2												1.3	3.3	1.4
Cash received from exercise of stock options		0.3	0	0.5									0.7	0.7	0.9
Share price			$ 3.37
Warrants outstanding																												1,602,489
Number of warrants issued as a percentage of outstanding shares					3.50%
Warrants, exercise price					2.40
Contra-revenue due to warrant agreement			$ 1.0