Leases - Additional Information (Detail) - Operating Lease [Member] $ in Millions |
12 Months Ended |
|---|---|
|
Dec. 31, 2020
USD ($)
ft²
Floor
| |
| Lessee Lease Description [Line Items] | |
| Area of office space | ft² | 847,000 |
| Operating leases, term of contract | 20 years |
| Expected lease commencement date | 2023-05 |
| Annual base rental payments first five years | $ 51 |
| Annual base rental payments five to ten years | 58 |
| Annual base rental payments ten to fifteen years | 66 |
| Annual base rental payments fifteen to twenty years | 74 |
| Total operating lease minimum commitments | $ 1,200 |
| Initial expansion option exercised, number of additional floors | Floor | 2 |
| Initial expansion option exercised, area of office space | ft² | 122,000 |
| Total operating lease minimum commitments, additional space | $ 185 |