v3.8.0.1
Revenue - Summary of Investment Advisory, Administration Fees and Securities Lending Revenue and Performance Fees by Type (Detail) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2018
Mar. 31, 2017
Schedule of Investment Advisory Administration Fees and Securities Lending Revenue and Performance Fees by Type [line Items]    
Total investment advisory, administration fees and securities lending revenue $ 2,947 $ 2,523
Investment advisory performance fees 70 70
Technology and risk management revenue 184 154
Distribution fees 311 287
Advisory and other revenue 71 58
Total revenue 3,583 3,092
Equity [Member]    
Schedule of Investment Advisory Administration Fees and Securities Lending Revenue and Performance Fees by Type [line Items]    
Total investment advisory, administration fees and securities lending revenue 1,540 1,281
Investment advisory performance fees 18 15
Equity [Member] | Active [Member]    
Schedule of Investment Advisory Administration Fees and Securities Lending Revenue and Performance Fees by Type [line Items]    
Total investment advisory, administration fees and securities lending revenue 438 400
Equity [Member] | iShares ETFs [Member]    
Schedule of Investment Advisory Administration Fees and Securities Lending Revenue and Performance Fees by Type [line Items]    
Total investment advisory, administration fees and securities lending revenue 926 721
Equity [Member] | Non-ETF Index [Member]    
Schedule of Investment Advisory Administration Fees and Securities Lending Revenue and Performance Fees by Type [line Items]    
Total investment advisory, administration fees and securities lending revenue 176 160
Fixed Income [Member]    
Schedule of Investment Advisory Administration Fees and Securities Lending Revenue and Performance Fees by Type [line Items]    
Total investment advisory, administration fees and securities lending revenue 757 677
Investment advisory performance fees 3 10
Fixed Income [Member] | Active [Member]    
Schedule of Investment Advisory Administration Fees and Securities Lending Revenue and Performance Fees by Type [line Items]    
Total investment advisory, administration fees and securities lending revenue 456 407
Fixed Income [Member] | iShares ETFs [Member]    
Schedule of Investment Advisory Administration Fees and Securities Lending Revenue and Performance Fees by Type [line Items]    
Total investment advisory, administration fees and securities lending revenue 208 185
Fixed Income [Member] | Non-ETF Index [Member]    
Schedule of Investment Advisory Administration Fees and Securities Lending Revenue and Performance Fees by Type [line Items]    
Total investment advisory, administration fees and securities lending revenue 93 85
Multi-asset [Member]    
Schedule of Investment Advisory Administration Fees and Securities Lending Revenue and Performance Fees by Type [line Items]    
Total investment advisory, administration fees and securities lending revenue 296 272
Investment advisory performance fees 5 5
Alternatives [Member]    
Schedule of Investment Advisory Administration Fees and Securities Lending Revenue and Performance Fees by Type [line Items]    
Total investment advisory, administration fees and securities lending revenue 203 166
Investment advisory performance fees 44 40
Alternatives [Member] | Core [Member]    
Schedule of Investment Advisory Administration Fees and Securities Lending Revenue and Performance Fees by Type [line Items]    
Total investment advisory, administration fees and securities lending revenue 178 144
Alternatives [Member] | Currency and Commodities [Member]    
Schedule of Investment Advisory Administration Fees and Securities Lending Revenue and Performance Fees by Type [line Items]    
Total investment advisory, administration fees and securities lending revenue 25 22
Cash Management [Member]    
Schedule of Investment Advisory Administration Fees and Securities Lending Revenue and Performance Fees by Type [line Items]    
Total investment advisory, administration fees and securities lending revenue 151 127
Retrocessions [Member]    
Schedule of Investment Advisory Administration Fees and Securities Lending Revenue and Performance Fees by Type [line Items]    
Distribution fees 192 155
12b-1 Fees (U.S. Mutual Funds Distribution Fees) [Member]    
Schedule of Investment Advisory Administration Fees and Securities Lending Revenue and Performance Fees by Type [line Items]    
Distribution fees 108 122
Other Distribution Fees [Member]    
Schedule of Investment Advisory Administration Fees and Securities Lending Revenue and Performance Fees by Type [line Items]    
Distribution fees 11 10
Long-term [Member]    
Schedule of Investment Advisory Administration Fees and Securities Lending Revenue and Performance Fees by Type [line Items]    
Total investment advisory, administration fees and securities lending revenue 2,796 2,396
Advisory [Member]    
Schedule of Investment Advisory Administration Fees and Securities Lending Revenue and Performance Fees by Type [line Items]    
Advisory and other revenue 21 24
Other [Member]    
Schedule of Investment Advisory Administration Fees and Securities Lending Revenue and Performance Fees by Type [line Items]    
Advisory and other revenue $ 50 $ 34