Stock-Based Compensation - Stock Options Activity (Details) (USD $) In Millions, except Share data, unless otherwise specified	9 Months Ended
	Sep. 30, 2014
Stock Options [Roll Forward]
Outstanding December 31, 2013 (shares)	5,371,538
Granted (shares)	61,275
Exercised (shares)	(87,569)
Canceled (shares)	(856,854)
Forfeited (shares)	(565,246)
Outstanding September 30, 2014 (shares)	3,923,144
Exercisable as of September 30, 2014 (shares)	3,383,760
Weighted Average Exercise Price [Roll Forward]
Outstanding December 31, 2013 (dollars per share)	$ 13.11
Granted (dollars per share)	$ 3.72
Exercised (dollars per share)	$ 3.97
Canceled (dollars per share)	$ 18.85
Forfeited (dollars per share)	$ 4.14
Outstanding September 30, 2014 (dollars per share)	$ 13.15
Exercisable as of September 30, 2014 (dollars per share)	$ 14.50
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options expiration term	10 years
Total unrecognized compensation expense related to non-vested stock	$ 0.7
Total compensation cost not yet recognized, period for recognition	1 year 2 months 12 days