v3.26.3
Contracts with Customers - Summary of Expected Revenue Related to Performance Obligations (Detail)
$ in Millions
Sep. 30, 2026
USD ($)
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]  
Expected revenue related to performance obligations $ 1,028
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2026-10-01  
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]  
Expected revenue related to performance obligations $ 725
Remaining performance obligation, expected timing of satisfaction, period 3 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2027-01-01  
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]  
Expected revenue related to performance obligations $ 222
Remaining performance obligation, expected timing of satisfaction, period 1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2028-01-01  
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]  
Expected revenue related to performance obligations $ 35
Remaining performance obligation, expected timing of satisfaction, period 1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2029-01-01  
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]  
Expected revenue related to performance obligations $ 16
Remaining performance obligation, expected timing of satisfaction, period 1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2030-01-01  
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]  
Expected revenue related to performance obligations $ 12
Remaining performance obligation, expected timing of satisfaction, period 1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2031-01-01  
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]  
Expected revenue related to performance obligations $ 18
Remaining performance obligation, expected timing of satisfaction, period
Brokerage  
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]  
Expected revenue related to performance obligations $ 808
Brokerage | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2026-10-01  
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]  
Expected revenue related to performance obligations $ 640
Remaining performance obligation, expected timing of satisfaction, period 3 months
Brokerage | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2027-01-01  
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]  
Expected revenue related to performance obligations $ 159
Remaining performance obligation, expected timing of satisfaction, period 1 year
Brokerage | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2028-01-01  
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]  
Expected revenue related to performance obligations $ 6
Remaining performance obligation, expected timing of satisfaction, period 1 year
Brokerage | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2029-01-01  
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]  
Expected revenue related to performance obligations $ 1
Remaining performance obligation, expected timing of satisfaction, period 1 year
Brokerage | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2030-01-01  
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]  
Expected revenue related to performance obligations $ 1
Remaining performance obligation, expected timing of satisfaction, period 1 year
Brokerage | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2031-01-01  
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]  
Expected revenue related to performance obligations $ 1
Remaining performance obligation, expected timing of satisfaction, period
Risk Management  
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]  
Expected revenue related to performance obligations $ 220
Risk Management | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2026-10-01  
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]  
Expected revenue related to performance obligations $ 85
Remaining performance obligation, expected timing of satisfaction, period 3 months
Risk Management | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2027-01-01  
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]  
Expected revenue related to performance obligations $ 63
Remaining performance obligation, expected timing of satisfaction, period 1 year
Risk Management | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2028-01-01  
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]  
Expected revenue related to performance obligations $ 29
Remaining performance obligation, expected timing of satisfaction, period 1 year
Risk Management | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2029-01-01  
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]  
Expected revenue related to performance obligations $ 15
Remaining performance obligation, expected timing of satisfaction, period 1 year
Risk Management | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2030-01-01  
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]  
Expected revenue related to performance obligations $ 11
Remaining performance obligation, expected timing of satisfaction, period 1 year
Risk Management | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2031-01-01  
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]  
Expected revenue related to performance obligations $ 17
Remaining performance obligation, expected timing of satisfaction, period