Annual report pursuant to Section 13 and 15(d)

Stockholders' Equity - Summary of Changes in Fair Value for Embedded Derivative (Detail)

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Stockholders' Equity - Summary of Changes in Fair Value for Embedded Derivative (Detail) - USD ($)
$ in Thousands
1 Months Ended 12 Months Ended
Feb. 10, 2017
Dec. 31, 2016
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]    
Fair value at the beginning of period and initial fair value, respectively $ 8,753 $ 5,445
(Gain) loss on exchange feature (2,209) 3,308
Fair value at the end of the period and year, respectively $ 6,544 $ 8,753