Stock-Based Compensation - Summary of Grants of Performance Based Restricted Stock Units Associated with NEOs and Key Employees (Parenthetical) (Detail) - Performance Based Restricted Stock Units [Member] - NEOs [Member]	Jul. 13, 2017 $ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value adjustment to closing price of common stock, percentage	98.00%
Fair value adjustment to closing price of common stock, per share	$ (0.65)
Closing price of common stock	$ 32.5