Leases - Additional Information (Detail) $ in Millions |
12 Months Ended | |
|---|---|---|
|
Dec. 31, 2019
USD ($)
ft²
Floor
|
Dec. 31, 2018
USD ($)
|
|
| Lessee Lease Description [Line Items] | ||
| Total operating lease minimum commitments | $ 2,157 | |
| Operating Lease [Member] | ||
| 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 |