Property and Equipment - Additional Information (Detail) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2015 |
|
| Property Plant And Equipment [Abstract] | |||
| Interest capitalized in conjunction with construction projects and software development | $ 2.2 | $ 2.8 | $ 1.9 |
| Commitments for facility construction projects | $ 31.9 | ||
| X | ||||||||||
- Definition Commitments for facility construction projects. No definition available.
|
| X | ||||||||||
- Definition Amount of interest capitalized during the period. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- References No definition available.
|