v3.8.0.1
Investments - Summary of Carrying Value of Total Investments (Detail) - USD ($)
$ in Millions
Mar. 31, 2018
Dec. 31, 2017
Investment [Line Items]    
Available-for-sale investments, Debt securities $ 151  
Available-for-sale investments   $ 103
Held-to-maturity investments 132 102
Trading securities ($266 debt securities of consolidated sponsored investment funds) 293  
Total trading investments   835
Total debt securities 576  
Equity securities at FVTNI ($284 equity securities of consolidated sponsored investment funds) 648  
Total investments 2,050 1,981
Other Equity and Debt Securities [Member]    
Investment [Line Items]    
Total trading investments   267
Deferred Compensation Plan Fund [Member]    
Investment [Line Items]    
Total trading investments   56
Consolidated Sponsored Investment Funds [Member] | Debt securities [Member]    
Investment [Line Items]    
Total trading investments 266 267
Consolidated Sponsored Investment Funds [Member] | Equity securities [Member]    
Investment [Line Items]    
Total trading investments   245
Equity securities at FVTNI ($284 equity securities of consolidated sponsored investment funds) 284  
Equity Method Investments [Member]    
Investment [Line Items]    
Total investments 703 816
Cost Method Investments [Member]    
Investment [Line Items]    
Total investments   93
Federal Reserve Bank Stock [Member]    
Investment [Line Items]    
Total investments 91  
Consolidated Entities [Member] | Carried Interest [Member]    
Investment [Line Items]    
Total investments $ 32 $ 32