Stock-Based Compensation - Stock Option Activity (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Stock Options [Roll Forward]
Outstanding. Beginning Balance (in shares)	5,818,472	5,679,579	4,916,088
Granted (in shares)	1,034,406	1,178,780	1,401,163
Exercised (in shares)	0	0	(45,429)
Canceled (in shares)	(1,069,192)	(752,415)	(475,703)
Forfeited (in shares)	(412,148)	(287,472)	(116,540)
Outstanding, Ending Balance (in shares)	5,371,538	5,818,472	5,679,579	4,916,088
Weighted Average Exercise Price [Roll Forward]
Oustanding, Beginning Balance (dollars per share)	$ 16.57	$ 19.87	$ 24.10
Granted (dollars per share)	$ 3.85	$ 5.80	$ 9.41
Exercised (dollars per share)	$ 0.00	$ 0.00	$ 10.13
Canceled (dollars per share)	$ 25.22	$ 26.61	$ 35.11
Forfeited (dollars per share)	$ 7.13	$ 9.24	$ 14.34
Outstanding, Ending Balance (dollars per share)	$ 13.11	$ 16.57	$ 19.87	$ 24.10
Weighted Average Remaining Contractual Life (Years)	6 years 1 month	5 years 11 months	6 years	5 years 7 months 6 days
Aggregate Intrinsic Value	$ 0.8	$ 0	$ 0	$ 0.7