Summary of Significant Accounting Policies - Carrying Value (Par Value for Convertible Debt) and Estimated Fair Value of Debt (Details 1) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Credit Agreement \| Term Loan
Carrying value (par value for convertible debt) and estimated fair value of debt
Carrying Value	$ 136,875	$ 142,500
Fair Value	136,875	142,500
Senior Subordinated Convertible Notes 2010
Carrying value (par value for convertible debt) and estimated fair value of debt
Carrying Value	34,732	150,000
Fair Value	63,990	$ 237,900
Senior Convertible Notes 2016
Carrying value (par value for convertible debt) and estimated fair value of debt
Carrying Value	230,000
Fair Value	$ 250,988

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant