Condensed Consolidated Statements Of Income (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Revenue
Investment advisory, administration fees and securities lending revenue	$ 2,024	$ 1,949	$ 5,991	$ 6,033
Investment advisory performance fees	103	91	224	224
BlackRock Solutionsand advisory	128	117	382	361
Distribution fees	19	23	58	78
Other revenue	46	45	143	158
Total revenue	2,320	2,225	6,798	6,854
Expenses
Employee compensation and benefits	828	771	2,439	2,425
Distribution and servicing costs	94	90	282	299
Amortization of deferred sales commissions	13	20	43	63
Direct fund expenses	144	139	440	435
General and administration	327	389	958	1,074
Amortization of intangible assets	39	39	117	117
Total expenses	1,445	1,448	4,279	4,413
Operating income	875	777	2,519	2,441
Non-operating income (expense)
Net gain (loss) on investments	75	(59)	143	18
Interest and dividend income	10	12	27	25
Interest expense	(57)	(49)	(158)	(128)
Total non-operating income (expense)	30	(112)	13	(121)
Income before income taxes	905	665	2,532	2,320
Income tax expense	250	95	742	564
Net income	655	570	1,790	1,756
Less:
Net income (loss) attributable to redeemable non-controlling interests	3		7
Net income (loss) attributable to nonredeemable non-controlling interests	10	(25)	15	(26)
Net income attributable to BlackRock, Inc.	642	595	1,768	1,782
Earnings per share attributable to BlackRock, Inc. common stockholders:
Basic	$ 3.72	$ 3.28	$ 10.02	$ 9.46
Diluted	$ 3.65	$ 3.23	$ 9.87	$ 9.33
Cash dividends declared and paid per share	$ 1.500	$ 1.375	$ 4.500	$ 4.125
Weighted-average common shares outstanding:
Basic	172,359,141	179,034,837	176,116,975	186,187,318
Diluted	175,450,532	181,825,329	178,956,699	188,792,952
Variable Interest Entity, Primary Beneficiary [Member]
Non-operating income (expense)
Net gain (loss) on consolidated variable interest entities	2	(16)	1	(36)
Less:
Net income (loss) attributable to nonredeemable non-controlling interests	2	(16)	1	(36)
Related Parties [Member]
Revenue
Investment advisory, administration fees and securities lending revenue	1,319	1,320	3,900	4,075
Other Third Parties [Member]
Revenue
Investment advisory, administration fees and securities lending revenue	$ 705	$ 629	$ 2,091	$ 1,958