Summary of Significant Accounting Policies - Summary of Company's Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - Interest rate caps - Fair Value Measurements Recurring - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate caps	$ 404	$ 340
Quoted prices in active markets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate caps	0	0
Significant other observable inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate caps	404	340
Significant unobservable inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate caps	$ 0	$ 0