Leases - Schedule of Supplemental Information Related to Operating Leases (Detail) - USD ($) $ in Millions |
12 Months Ended | |
|---|---|---|
Dec. 31, 2020 |
Dec. 31, 2019 |
|
| Supplemental cash flow information: | ||
| Cash paid for amounts included in the measurement of operating lease liabilities | $ 154 | $ 142 |
| Supplemental noncash information: | ||
| ROU assets in exchange for operating lease liabilities in connection with the adoption of ASU 2016-02, "Leases" | $ 93 | $ 117 |
| Weighted-average remaining lease term | 8 years | 9 years |
| Weighted-average discount rate | 3.00% | 3.00% |
| Accounting Standards Update 2016-02 [Member] | ||
| Supplemental noncash information: | ||
| ROU assets in exchange for operating lease liabilities in connection with the adoption of ASU 2016-02, "Leases" | $ 661 | |