Condensed Consolidated Statements Of Financial Condition (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Assets
Cash and cash equivalents	$ 4,223	$ 3,506
Accounts receivable	2,464	1,960
Due from related parties	121	142
Investments	1,864	1,631
Separate account assets	128,013	118,871
Collateral held under securities lending agreements	22,562	20,918
Deferred sales commissions, net	26	38
Property and equipment (net of accumulated depreciation of $564 and $483 at September 30, 2012 and December 31, 2011, respectively)	560	537
Intangible assets (net of accumulated amortization of $859 and $751 at September 30, 2012 and December 31, 2011, respectively)	17,442	17,356
Goodwill	12,908	12,792
Other assets	670	452
Total assets	192,828	179,896
Liabilities
Accrued compensation and benefits	1,204	1,383
Accounts payable and accrued liabilities	1,427	923
Due to related parties	15	22
Short-term borrowings	100	100
Long-term borrowings	6,186	4,690
Separate account liabilities	128,013	118,871
Collateral liabilities under securities lending agreements	22,562	20,918
Deferred income tax liabilities	5,311	5,323
Other liabilities	849	721
Total liabilities	167,519	154,534
Commitments and contingencies (Note 11)
Temporary equity
Redeemable non-controlling interests	28	92
Permanent Equity
Common stock, $0.01 par value; Shares authorized: 500,000,000 at September 30, 2012 and December 31, 2011; Shares issued: 168,661,718 and 139,880,380 at September 30, 2012 and December 31, 2011, respectively; Shares outstanding: 167,102,878 and 138,463,135 at September 30, 2012 and December 31, 2011, respectively	2	1
Preferred stock (Note 15)
Additional paid-in capital	19,322	20,275
Retained earnings	6,010	5,046
Accumulated other comprehensive loss	(58)	(127)
Escrow shares, common, at cost (3,603 shares held at September 30, 2012 and December 31, 2011)	(1)	(1)
Treasury stock, common, at cost (1,555,237 and 1,413,642 shares held at September 30, 2012 and December 31, 2011, respectively)	(274)	(218)
Total BlackRock, Inc. stockholders' equity	25,057	25,048
Nonredeemable non-controlling interests	170	184
Total permanent equity	25,261	25,270
Total liabilities, temporary equity and permanent equity	192,828	179,896
Variable Interest Entity, Primary Beneficiary [Member]
Assets
Cash and cash equivalents	292	54
Bank loans and other investments	1,683	1,639
Liabilities
Borrowings	1,843	1,574
Other liabilities	9	9
Temporary equity
Redeemable non-controlling interests	20
Permanent Equity
Appropriated retained earnings	56	72
Nonredeemable non-controlling interests	$ 34	$ 38