v3.8.0.1
Commitments and Guarantees, Contingent Liabilities and Litigation and Regulatory Matters (Narrative Excluding Litigation) (Details)
$ in Millions
12 Months Ended
Dec. 31, 2017
USD ($)
Dec. 31, 2016
USD ($)
Dec. 31, 2015
USD ($)
Commitments and Guarantees and Contingent Liabilities [Line Items]      
Rental expense, net of sub-lease income $ 258 $ 252 $ 232
Operating and capital leases reserve accrual 644    
Sub-lease income accrual 0    
Accrued reserves      
Commitments and Guarantees and Contingent Liabilities [Line Items]      
Operating and capital leases reserve accrual 2    
Sub-lease income accrual $ 0    
Indemnification | Securities Lending Transactions      
Commitments and Guarantees and Contingent Liabilities [Line Items]      
Guarantor Obligations, Liquidation Proceeds, Percentage 102.00%    
Indemnification | Serviced Mortgages Loans      
Commitments and Guarantees and Contingent Liabilities [Line Items]      
Mortgages subject to loss-sharing arrangements $ 12,892 $ 11,445  
Weighted-average debt service coverage ratio of mortgages subject to loss-sharing arrangements 1.82 1.82  
Weighted-average loan-to-value ratio of mortgages subject to loss-sharing arrangements 59.00% 59.00%  
Total share of losses settled $ 0 $ 0 $ 1
Indemnification | Minimum | Serviced Mortgages Loans      
Commitments and Guarantees and Contingent Liabilities [Line Items]      
Share losses incurred of loan balances, Percent 2.00%    
Indemnification | Maximum | Serviced Mortgages Loans      
Commitments and Guarantees and Contingent Liabilities [Line Items]      
Share losses incurred of loan balances, Percent 20.00%    
Yield maintenance guarantee      
Commitments and Guarantees and Contingent Liabilities [Line Items]      
Guarantees related to certain investments the Company sold $ 31 $ 51