Summary of Borrowings (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Oct. 23, 2017
Debt Instrument [Line Items]
Principal amount	$ 101,700
Note payable to related party - net carrying amount	72,089	$ 79,666
2019 Notes and Tranche B Notes
Debt Instrument [Line Items]
Principal amount	11,495	54,407
Unamortized debt issuance costs and debt discount	(197)	(1,662)
Net carrying amount	11,298	52,745
2021 Notes
Debt Instrument [Line Items]
Principal amount	18,690	23,690	$ 23,700
Unamortized premium	409	721
Net carrying amount	$ 19,099	$ 24,411

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.

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