Fair Value Measurements (Fair Value of Other Financial Instruments) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011
Convertible senior notes [Member] | Convertible senior notes (2008 Notes) [Member] | Carrying Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long-term debt	$ 5,133	[1]	$ 65,604	[1]
Convertible senior notes [Member] | Convertible senior notes (2008 Notes) [Member] | Fair Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long-term debt	5,163	[1]	69,880	[1]
Convertible senior notes [Member] | Convertible senior secured notes (2010 Notes) [Member] | Carrying Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long-term debt	0	[1]	34,134	[1]
Convertible senior notes [Member] | Convertible senior secured notes (2010 Notes) [Member] | Fair Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long-term debt	0	[1]	37,561	[1]
Term loan [Member] | Carrying Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long-term debt	25,000		0
Term loan [Member] | Fair Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long-term debt	25,000		0
Capital lease obligations [Member] | Carrying Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Capital lease obligations	1,784		1,642
Capital lease obligations [Member] | Fair Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Capital lease obligations	$ 1,736		$ 1,611

[1] The carrying value of the 2008 and 2010 Notes represents the discounted debt component only, while the fair value of the Notes is based on the market value of the respective notes, including convertible equity features.