v3.20.4
Earnings Per Share - Computation of Basic and Diluted EPS under Treasury Stock Method (Detail) - USD ($)
$ / shares in Units, $ in Millions
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Earnings Per Share Basic And Diluted [Line Items]      
Net income attributable to BlackRock, Inc. $ 4,932 $ 4,476 $ 4,305
Basic weighted-average shares outstanding 153,489,422 156,014,343 160,301,116
Total diluted weighted-average shares outstanding 154,840,582 157,459,546 161,948,732
Basic earnings per share $ 32.13 $ 28.69 $ 26.86
Diluted earnings per share $ 31.85 $ 28.43 $ 26.58
Restricted Stock Units (RSUs) [Member]      
Earnings Per Share Basic And Diluted [Line Items]      
Dilutive effect of 1,275,733 1,445,203 1,647,616
Stock Options [Member]      
Earnings Per Share Basic And Diluted [Line Items]      
Dilutive effect of 75,427