Other Assets - Intangible Assets Disclosure (Detail) - USD ($) $ in Millions |
Jun. 30, 2021 |
Dec. 31, 2020 |
|---|---|---|
| Finite-Lived Intangible Assets [Line Items] | ||
| Gross carrying value | $ 2,072 | $ 2,188 |
| Accumulated amortization | (1,549) | (1,558) |
| Net carrying value | 523 | 630 |
| Customer Lists [Member] | ||
| Finite-Lived Intangible Assets [Line Items] | ||
| Gross carrying value | 1,472 | 1,478 |
| Accumulated amortization | (1,112) | (1,089) |
| Net carrying value | 360 | 389 |
| Acquired leases and other [Member] | ||
| Finite-Lived Intangible Assets [Line Items] | ||
| Gross carrying value | 600 | 710 |
| Accumulated amortization | (437) | (469) |
| Net carrying value | $ 163 | $ 241 |