Leases - Additional Information (Detail) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2020 |
Dec. 31, 2019 |
Dec. 31, 2018 |
|
| Lessee, Lease, Description [Line Items] | |||
| Operating lease month of expiry | 2032-03 | ||
| Operating lease weighted average remaining lease term | 8 years 18 days | ||
| Operating lease weighted average discount rate | 6.34% | ||
| Net rent expense | $ 38.5 | $ 43.6 | |
| Sublease income | $ 14.8 | $ 13.1 | |
| Lease Renewal Option One [Member] | |||
| Lessee, Lease, Description [Line Items] | |||
| Operating lease optional remaining renewal term | 2033-06 | ||
| Office Space [Member] | |||
| Lessee, Lease, Description [Line Items] | |||
| Lessee operating lease not yet commenced year of commencement | 2021 | ||
| Lessee operating lease not yet commenced term of contracts | 4 years | ||
| Lessee operating lease not yet commenced payments due | $ 1.1 | ||