Share-Based Compensation - Additional Information (Detail) - USD ($) $ in Millions |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2020 |
Jun. 30, 2019 |
Jun. 30, 2020 |
Jun. 30, 2019 |
|
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||||
| Share-based compensation expense | $ 12.2 | $ 9.9 | $ 22.5 | $ 20.5 |
| Unrecognized compensation cost on non-vested stock awards | 86.6 | $ 86.6 | ||
| Unrecognized compensation cost on non-vested stock awards, weighted-average period of recognition | 1 year 10 months 24 days | |||
| Total vesting date fair value of stock units | $ 1.4 | $ 1.9 | $ 11.0 | $ 10.9 |
| SARs [Member] | ||||
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||||
| SARs granted | 0 | 0 | 0 | 0 |
| Total intrinsic value of awards exercised for SARs | $ 10.1 | $ 5.3 | $ 11.7 | $ 17.2 |
| X | ||||||||||
- Definition Intrinsic value of awards exercised for stock appreciation rights. No definition available.
|
| X | ||||||||||
- Definition Amount of expense for award under share-based payment arrangement. Excludes amount capitalized. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
|
| X | ||||||||||
- Definition Amount of cost not yet recognized for nonvested award under share-based payment arrangement. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
|
| X | ||||||||||
- Definition Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
|
| X | ||||||||||
- Definition Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
|
| X | ||||||||||
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available.
|
| X | ||||||||||
- Definition Net number of non-option equity instruments granted to participants. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
|
| X | ||||||||||
- Details
|