Fair Value Measurements (Fair Value of Other Financial Instruments) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012
Convertible senior notes [Member] | 2008 Notes [Member] | Carrying Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long-term debt	$ 0	[1]	$ 5,133	[1]
Convertible senior notes [Member] | 2008 Notes [Member] | Fair Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long-term debt	0	[1]	5,163	[1]
Term loan [Member] | Term Loan 2012 [Member] | Carrying Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long-term debt	45,833		25,000
Term loan [Member] | Term Loan 2012 [Member] | Fair Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long-term debt	45,833		25,000
Capital lease obligations [Member] | Carrying Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Capital lease obligations	0		1,784
Capital lease obligations [Member] | Fair Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Capital lease obligations	$ 0		$ 1,736

[1] The carrying value of the 2008 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.