Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Cash Flows from Operating Activities:
Net (loss) income	$ (247,859)	$ (179,789)	$ 23,980
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Depreciation and amortization	56,493	59,057	62,373
Deferred income tax (benefit) expense	(27,156)	(32,593)	(4,315)
Provision for doubtful accounts	1,401	203	178
Share-based compensation	15,628	20,156	18,006
Capitalized software write-off			6,091
Non-cash restructuring charges, net	548	2,480	1,461
Goodwill and other asset impairment	274,285	229,317	5,375
Changes in operating assets and liabilities:
Cash restricted or segregated under regulations and other	11,700	(2,625)	25,843
Deposits with clearing organizations	(3,611)	(11,303)	656
Securities owned, at fair value	(4,689)	18,403	(18,058)
Receivables from brokers, dealers and clearing organizations	(230,137)	(6,671)	(503,140)
Receivables from customers	(59,252)	134,913	(290,031)
Accounts payable and accrued expenses	(22,905)	(18,079)	(31,995)
Payables to brokers, dealers and clearing organizations	241,231	(59,605)	889,457
Payables to customers	15,595	(64,592)	(37,698)
Securities sold, not yet purchased, at fair value	4,695	(18,915)	18,347
Income taxes receivable/payable	(1,459)	(6,053)	10,446
Other, net	2,284	2,755	(867)
Net cash provided by operating activities	26,792	67,059	176,109
Cash Flows from Investing Activities:
Acquisition of subsidiaries and minority interests, net of cash acquired		(36,185)	(48,926)
Capital purchases	(33,424)	(22,857)	(19,280)
Capitalization of software development costs	(24,635)	(29,061)	(33,897)
Proceeds from sale of investments		2,095
Net cash used in investing activities	(58,059)	(86,008)	(102,103)
Cash Flows from Financing Activities:
Proceeds of short-term bank loans	20,548	1,606
Proceeds from term loans		25,469
Repayments of term loans	(7,185)	(4,043)	(46,900)
Proceeds from interim funding facility	605
Proceeds from sales-lease back transactions	1,855	2,571
Debt issuance costs		(2,908)
Common stock issued	2,674	9,753	10,896
Common stock repurchased	(23,457)	(38,928)	(50,284)
Shares withheld for net settlements of share-based awards	(2,817)	(5,984)	(4,095)
Net cash used in financing activities	(7,777)	(12,464)	(90,383)
Effect of exchange rate changes on cash and cash equivalents	731	(1,409)	2,508
Net decrease in cash and cash equivalents	(38,313)	(32,822)	(13,869)
Cash and cash equivalents-beginning of year	284,188	317,010	330,879
Cash and cash equivalents-end of year	245,875	284,188	317,010
Supplemental cash flow information:
Interest paid	2,673	2,453	1,343
Income taxes paid	5,495	15,508	19,345
Majestic acquisition replacement awards			$ 2,994