Organization, Basis of Presentation and Summary of Significant Accounting Policies - Aggregate Fair Value and Carrying Value of Short and Long-term Debt (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Carrying Amount [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Short-term debt - related party	$ 1,000
Long-term debt - related party	1,200	$ 1,295
Long-term debt	1,558	1,295
Total long-term debt	3,758	2,590
Fair Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Short-term debt - related party	1,000
Long-term debt - related party	1,200	1,295
Long-term debt	1,558	1,295
Total long-term debt	$ 3,758	$ 2,590