Debt and Other Obligations - Interest Expense (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Debt Instrument [Line Items]
Commitment fees	$ 28	$ 30	$ 58	$ 65
Amortization of debt discounts	1,290	794	2,521	1,310
Total	13,727	10,164	26,112	18,219
Senior Loans [Member]
Debt Instrument [Line Items]
Interest expense, term loans	4,619	4,964	9,290	10,012
Junior Loans [Member]
Debt Instrument [Line Items]
Interest expense, term loans	775	905	1,578	1,842
Fixed Rate Loan [Member]
Debt Instrument [Line Items]
Interest expense, term loans	1,586	0	1,744	0
Equipment Notes, Series A [Member]
Debt Instrument [Line Items]
Interest expense, term loans	4,321	2,698	8,629	3,881
Equipment Notes, Series B [Member]
Debt Instrument [Line Items]
Interest expense, term loans	$ 1,108	$ 773	$ 2,292	$ 1,109

Amount of amortization expense attributable to debt discount (premium) and debt issuance costs.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3602-108585

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Amount of the cost of borrowed funds accounted for as interest expense for debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.8)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

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Aggregate amount of interest paid or due on all long-term debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.8)
-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

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Amount of the fee for available but unused credit capacity under the credit facility.

+ References

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 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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