Share-Based Compensation (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended						12 Months Ended
	Dec. 31, 2007 Restricted common stock Executive officers	Dec. 31, 2012 Cash Awards	Dec. 31, 2011 Cash Awards	Dec. 31, 2010 Cash Awards	Dec. 31, 2012 Stock Awards	Dec. 31, 2012 2005 Plan	Dec. 31, 2012 2005 Plan Restricted common stock	Dec. 31, 2011 2005 Plan Restricted common stock	Dec. 31, 2010 2005 Plan Restricted common stock	Dec. 31, 2012 2005 Plan Stock options	Dec. 31, 2011 2005 Plan Stock options	Dec. 31, 2010 2005 Plan Stock options
Share-Based Compensation
Amount of discretionary cash bonus awards paid		$ 1.2	$ 2.8	$ 2.9
Compensation expense							2.0	1.4	1.5	0.5	0.6	0.3
Portion of award vesting per year over the first through fourth anniversaries from the date of grant (as a percent)					25.00%
Cumulative percentage of award vesting on the fourth anniversary from the date of grant					100.00%
Shares authorized for the issuance						5,800,000
Shares issued	250,000						959,000	446,725	402,859
Options outstanding (in shares)										1,675,419	1,715,358	1,741,543
Shares vested										500,000
Unvested restricted shares outstanding							1,800,000
Exercise prices, low end of range (in dollars per share)										$ 2.13
Exercise prices, high end of range (in dollars per share)										$ 5.00
Restricted common stock vested							393,127	354,051
Shares held to satisfy the employees' tax liability							53,826	46,215
Shares of common stock available for future grant										1,100,000
Estimated expenses that will be expensed over the remaining vesting period										$ 0.8
Assumptions used in the valuation of fair value of each option award
Weighted average fair value of awards (in dollars per share)										$ 2.16	$ 2.07	$ 2.19
Pre-vest forfeiture rate (as a percent)										7.36%	6.92%	5.01%
Average grant price (in dollars per share)										$ 3.23	$ 3.35	$ 3.19
Expected volatility (as a percent)										74.68%	74.47%	75.38%
Risk-free rate (as a percent)										1.13%	1.65%	2.55%
Expected term										6 years 4 months 24 days	6 years 4 months 2 days	6 years 4 months 10 days