Stock-Based Compensation - Additional Information (Detail) - Restricted Stock Units (RSUs) [Member] |
3 Months Ended |
---|---|
Mar. 31, 2019
USD ($)
| |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |
Total compensation cost related to RSU's not yet recognized | $ 36,742,000 |
Weighted average number of years for recognition of outstanding nonvested RSUs | 1 year 10 months 2 days |