Debt and Other Contractual Obligations - Summary of Future Contractual Obligations (Detail) $ in Thousands	Jun. 30, 2018 USD ($)
Debt Disclosure [Abstract]
Operating lease obligations, Total	$ 296
Operating lease obligations, Remainder of 2018	222
Operating lease obligations, 2019	74
Loan principal repayments, Total	2,255
Loan principal repayments, Remainder of 2018	116
Loan principal repayments, 2019	237
Loan principal repayments, 2020	243
Loan principal repayments, 2021	250
Loan principal repayments, 2022	257
Loan principal repayments, Thereafter	1,152
Capital lease obligations, Total	1,198
Capital lease obligations, Remainder of 2018	154
Capital lease obligations, 2019	317
Capital lease obligations, 2020	331
Capital lease obligations, 2021	344
Capital lease obligations, 2022	52
Minimum purchase obligation, Total	5,375
Minimum purchase obligation, Remainder of 2018	3,401
Minimum purchase obligation, 2019	1,974
Total	9,124
Remainder of 2018	3,893
2019	2,602
2020	574
2021	594
2022	309
Thereafter	$ 1,152

Amount of minimum lease payments for capital leases.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=84164817&loc=d3e45280-112737

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Amount of required minimum rental payments for leases having an initial or remaining non-cancelable letter-terms in excess of one year.

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Minimum amount of purchase arrangement in which the entity has agreed to expend funds to procure goods or services from a supplier.

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