Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Cash flows from operating activities:
Net income (loss) from continuing operations	$ (78,537)	$ (31,690)	$ (39,039)
Net income (loss) from discontinued operations, net of tax	(23,646)
Adjustments to reconcile net income (loss) to net cash (used in) / provided by operating activities:
Bargain purchase gain	(22,244)
Depreciation and amortization	26,864	11,543	5,761
Share-based compensation	28,308	20,608	3,637
Deferred rent obligations	(4,061)	(8,574)	(543)
Net loss on disposal of fixed assets	103	299	249
Goodwill impairment	7,151
Purchases of securities owned, at fair value	(8,953,879)	(3,415,775)	(84,350)
Proceeds from sales of securities owned, at fair value	8,726,114	2,943,376	97,299
Proceeds from sales of securities sold, not yet purchased, at fair value	4,690,844	2,678,922
Payments to cover securities sold, not yet purchased, at fair value	(4,553,832)	(2,556,056)
Net (gains) losses on securities, derivatives and other investments	(3,164)	(20,339)	(1,891)
Purchases of securities owned, at fair value, Consolidated Funds	(480,251)	(445,913)
Proceeds from sales of securities owned, at fair value, Consolidated Funds	482,630	437,147
Purchases of other investments, Consolidated Funds	(18,356)	(30,583)	(2,181)
Proceeds from sales of other investments, Consolidated Funds	127,664	285,915	75,743
Net realized and unrealized (gains) loss on investments and other transactions, Consolidated Funds	(4,746)	(34,316)	(39,506)
(Increase) decrease in operating assets:
Cash acquired from business acquisition	117,496		97,903
Cash collateral pledged	(25)	(8,132)	203
Securities owned, at fair value, held at broker dealer	152,080	50,895	(34,133)
Receivable from brokers	127,645	(63,412)	13,279
Fees receivable	9,391	(9,242)	1,686
Due from related parties	3,286	(1,510)	9,021
Other assets	(2,286)	5,040	(1,682)
Cash and cash equivalents, Consolidated Funds	6,913	(4,024)	(92)
Other assets, Consolidated Funds	469	215	(645)
Increase (decrease) in operating liabilities:
Securities sold, not yet purchased, at fair value, held at broker dealer	(157,134)	75,075	1,980
Payable to brokers	46,169	81,838	(1,304)
Compensation payable	(12,107)	(4,248)	4,425
Fees payable	(4,263)	3,410	(2,394)
Due to related parties	(7,273)	1,084	(2,446)
Accounts payable, accrued expenses and other liabilities	7,143	(14,758)	9,474
Due to related parties, Consolidated Funds			(136)
Accounts payable, accrued expenses and other liabilities, Consolidated Funds	(1,582)	1,652	(20)
Net cash provided by / (used in) operating activities	232,884	(51,553)	110,298
Cash flows from investing activities:
Securities purchased under agreement to resell	(68,505)	(97,755)
Purchases of other investments	(67,914)	(321,914)	(233)
Proceeds from sales of other investments	57,917	316,063	9,477
Purchase of fixed assets	(6,539)	(5,853)	(399)
Net cash provided by / (used in) investing activities	(85,041)	(109,459)	8,845
Cash flows from financing activities:
Securities sold under agreement to repurchase	36,618	192,165	(1,425)
Borrowings on short-term borrowings and other debt	493	8,059
Repayments on short-term borrowings and other debt	(26,576)	(25,663)	(203)
Purchase of treasury stock	(11,365)
Proceeds from issuance of common stock			80,607
Purchase of non-controlling interest (see Note 2)			(10,370)
Capital withdrawals to members			(23,943)
Capital withdrawals to non-controlling interests in operating entities	(5,009)		486
Repayments on line of credit, Consolidated Funds			(10,207)
Capital contributions by non-controlling interest in Consolidated Funds	4,038	10,062	1,613
Capital withdrawals to non-controlling interests in Consolidated Funds	(55,507)	(134,624)	(55,011)
Net cash provided by / (used in) financing activities	(57,308)	49,999	(18,453)
Change in cash and cash equivalents	90,535	(111,013)	100,690
Cash and cash equivalents at beginning of year	36,354	147,367	46,677
Cash and cash equivalents at end of year	126,889	36,354	147,367
Supplemental information
Cash paid during the period for interest	9,007	6,943	1,277
Cash paid during the period for taxes	871	1,310
Supplemental non-cash information:
Purchase of treasury stock, at cost, upon close of acquisition (see Note 21)	(1,906)
Purchase of treasury stock, at cost, through net settlement (see Note 21)	(3,631)
Net assets acquired upon acquisition (net of cash) (see Note 2)	58,486		11,167
Non compete agreements and covenants with limiting conditions acquired (see Note 2)	2,310
Common stock issuance upon close of acquisition (see Note 2)	156,048		114,497
Net assets of consolidated entities	3,470
Net assets of deconsolidated entity		6,816
Net settlement of cash collateral pledged with repayments on the line of credit		6,746
Assets acquired under capital lease obligations		6,337
Common stock issuance to purchase noncontrolling interest (see Note 2)			20,490
Capital contributions made through REOP Program (See Note 15)			$ 4,906