v3.3.1.900
Selected Quarterly Financial Data - Schedule of Selected Quarterly Financial Data (Detail) - USD ($)
$ / shares in Units, $ in Millions
 3 Months Ended 12 Months Ended
Dec. 31, 2015
Sep. 30, 2015
Jun. 30, 2015
Mar. 31, 2015
Dec. 31, 2014
Sep. 30, 2014
Jun. 30, 2014
Mar. 31, 2014
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Quarterly Financial Information Disclosure [Abstract]                      
Revenue $ 2,863 $ 2,910 $ 2,905 $ 2,723 $ 2,784 $ 2,849 $ 2,778 $ 2,670 $ 11,401 $ 11,081 $ 10,180
Operating income 1,137 1,222 1,238 1,067 1,144 1,157 1,122 1,051 4,664 4,474 3,857
Net income 869 832 826 825 806 873 841 744 3,352 3,264 2,951
Net income attributable to BlackRock $ 861 $ 843 $ 819 $ 822 $ 813 $ 917 $ 808 $ 756 $ 3,345 $ 3,294 $ 2,932
Earnings per share attributable to BlackRock, Inc. common stockholders: Basic $ 5.19 $ 5.08 $ 4.92 $ 4.92 $ 4.86 $ 5.46 $ 4.79 $ 4.47 $ 20.10 $ 19.58 $ 17.23
Earnings per share attributable to Black Rock, Inc. common stockholders: Diluted $ 5.11 $ 5.00 $ 4.84 $ 4.84 $ 4.77 $ 5.37 $ 4.72 $ 4.40 $ 19.79 $ 19.25 $ 16.87
Weighted-average common shares outstanding: Basic 165,826,808 166,045,291 166,616,558 167,089,037 167,197,844 167,933,040 168,712,221 169,081,421 166,390,009 168,225,154 170,185,870
Weighted-average common shares outstanding: Diluted 168,632,558 168,665,303 169,114,759 169,723,167 170,367,445 170,778,766 171,150,153 171,933,803 169,038,571 171,112,261 173,828,902
Dividend declared per share $ 2.18 $ 2.18 $ 2.18 $ 2.18 $ 1.93 $ 1.93 $ 1.93 $ 1.93 $ 8.72 $ 7.72 $ 6.72
Common stock price per share: High 363.72 354.54 377.85 380.33 364.40 336.47 319.85 323.89 363.72 364.40  
Common stock price per share: Low 295.92 293.52 344.54 340.51 303.91 301.10 293.71 286.39 295.92 303.91  
Common stock price per share: Close $ 340.52 $ 297.47 $ 345.98 $ 365.84 $ 357.56 $ 328.32 $ 319.60 $ 314.48 $ 340.52 $ 357.56  
Tax benefit related to certain nonrecurring items       $ 69 $ 39   $ 34