Condensed Consolidated Statements of Cash Flows (USD $) In Thousands	6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010
Cash flows from operating activities:
Net income (loss)	$ 23,375	$ (28,669)
Adjustments to reconcile net income (loss) to net cash provided by / (used in) operating activities:
Bargain purchase gain	(22,244)
Depreciation and amortization	4,069	4,884
Share-based compensation	14,086	9,310
Net loss on disposal of fixed assets		266
Purchases of securities owned, at fair value	(5,053,676)	(666,553)
Proceeds from sales of securities owned, at fair value	4,834,296	409,108
Proceeds from the sale of securities sold, not yet purchased, at fair value	2,485,115	306,842
Payments to cover securities sold, not yet purchased, at fair value	(2,435,760)	(295,263)
Net (gains) losses on securities, derivatives and other investments	(13,509)	(1,975)
(Increase) decrease in operating assets:
Cash acquired upon acquisition (see Note 2)	117,496
Cash collateral pledged	(41)
Securities owned, at fair value, held at broker dealer	(73,150)	82,450
Receivable from brokers	64,704	(11,697)
Fees receivable	9,246	5,325
Due from related parties	(136)	259
Other assets	(8,765)	5,404
Increase (decrease) in operating liabilities:
Securities sold, not yet purchased, at fair value, held at broker dealer	28,189	11,727
Payable to brokers	154,035	101,469
Compensation payable	(52,799)	(51,711)
Fees payable	(3,338)	(3,840)
Due to related parties	(6,630)	(800)
Accounts payable, accrued expenses and other liabilities	3,339	(20,775)
Net cash provided by / (used in) operating activities	147,615	(76,711)
Cash flows from investing activities:
Securities purchased under agreements to resell	20,423
Purchases of other investments	(40,650)	(3,164)
Proceeds from sales of other investments	39,567	5,686
Purchase of fixed assets	(4,263)	(172)
Net cash provided by / (used in) investing activities	15,077	2,350
Cash flows from financing activities:
Securities sold under agreements to repurchase	(22,726)	28,640
Repayments on short-term borrowings and other debt	(25,608)	(25,000)
Borrowings on short-term borrowings and other debt	493
Capital withdrawals to non-controlling interests	(2,009)
Net cash (used in) / provided by financing activities	(88,871)	(57,656)
Change in cash and cash equivalents	73,821	(132,017)
Cash and cash equivalents at beginning of year	36,354	147,367
Cash and cash equivalents at end of period	110,175	15,350
Supplemental non-cash information:
Deconsolidation of CHRP GP (see Note 3b)		1,712
Net settlement of cash collateral pledged with repayments on the line of credit		6,745
Purchase of treasury stock upon close of acquisition (see Note 15)	1,901
Common stock issuance upon close of acquisition (see Note 2)	156,048
Net assets acquired upon acquisition (net of cash)	58,486
Non-compete agreements acquired	2,310
Consolidated Funds
Adjustments to reconcile net income (loss) to net cash provided by / (used in) operating activities:
Purchases of securities owned, at fair value	(245,778)	(212,811)
Proceeds from sales of securities owned, at fair value	248,297	202,007
Purchases of other investments	(11,101)	(18,634)
Proceeds from sales of other investments	87,963	117,873
Net realized and unrealized (gains) losses on investments and other transactions	(5,373)	(15,578)
(Increase) decrease in operating assets:
Cash and cash equivalents	6,421	(6,089)
Other assets	449	99
Increase (decrease) in operating liabilities:
Accounts payable, accrued expenses and other liabilities	(1,165)	661
Cash flows from financing activities:
Capital contributions by non-controlling interests in Consolidated Funds	4,038	2,646
Capital withdrawals to non-controlling interests	(43,059)	(63,942)
Cash and cash equivalents at beginning of year	7,210
Cash and cash equivalents at end of period	789
Supplemental non-cash information:
Net assets of consolidated entity	$ 3,470