XML 117 R102.htm IDEA: XBRL DOCUMENT v3.10.0.1
Commitments, contingencies, and guarantees (Narrative) (Detail) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Oct. 25, 2017
Financial Instruments Owned and Pledged as Collateral [Line Items]        
Concentration Risk Percentage Marsh 10.00%      
Derivative Liability, Fair Value, Amount Subject to a Master Netting Agreement $ 95 $ 24    
Securities Sold under Agreements to Repurchase 1,418 $ 1,408    
Concentration Risk, Percentage   0.00% 0.00%  
Purchase Commitment, Remaining Minimum Amount Committed 711      
Carrying value of limited partnerships and partially-owned investment companies included in other investments 4,200      
Funding commitments relating to limited partnerships and partially-owned investment companies 3,700      
Line of Credit Facility, Current Borrowing Capacity       $ 1,000
Line of Credit Facility, Maximum Borrowing Capacity 2,000      
Line of Credit Facility, Capacity Available for Specific Purpose Other than for Trade Purchases 1,000      
Total rental expense related to operating leases 169 $ 211 $ 209  
Letter of Credit [Member]        
Financial Instruments Owned and Pledged as Collateral [Line Items]        
Line of Credit Facility, Amount Outstanding $ 398