v3.20.4
Leases - Components of Lease Cost (Detail) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Lease cost:    
Operating lease cost [1],[2] $ 147 $ 141
Variable lease cost [1],[3] 40 39
Total lease cost [1] $ 187 $ 180
[1]

Rent expense and certain office equipment expense under lease agreements amounted to $135 million in 2018.
[2]

Amounts include short-term leases, which are immaterial for both 2020 and 2019.
[3]

Amounts include operating lease payments, which may be adjusted based on usage, changes in an index or market rate, as well as common area maintenance charges and other variable costs not included in the measurement of ROU assets and operating lease liabilities.