Long-term Debt - Loss on debt extinguishment (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Mar. 31, 2018	Sep. 30, 2018
Gain (Loss) on Extinguishment of Debt [Abstract]
Loss on debt extinguishment	$ 4,300	$ 4,305
Loss on early extinguishment related to the write-off of unamortized debt discount	2,100
Loss on early debt extinguishment related to write off of deferred loan costs	$ 2,200

Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 50
-Section 40
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=117329964&loc=d3e12355-112629

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 50
-Section 40
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-URI http://asc.fasb.org/extlink&oid=117329964&loc=d3e12317-112629

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3602-108585

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