Condensed Consolidated Statements of Financial Condition (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Assets
Cash and cash equivalents	$ 262,890	$ 284,188
Cash restricted or segregated under regulations and other	66,176	71,496
Deposits with clearing organizations	23,461	25,538
Securities owned, at fair value	8,718	5,277
Receivables from brokers, dealers and clearing organizations	1,290,402	871,315
Receivables from customers	543,936	472,509
Premises and equipment, net	42,718	43,023
Capitalized software, net	45,994	51,258
Goodwill		274,292
Other intangibles, net	36,536	39,594
Income taxes receivable	9,658	6,838
Deferred taxes	36,156	16,493
Other assets	17,951	16,248
Total assets	2,384,596	2,178,069
Liabilities:
Accounts payable and accrued expenses	152,564	181,224
Short-term bank loans	15,439	1,606
Payables to brokers, dealers and clearing organizations	1,159,725	1,079,773
Payables to customers	601,042	207,738
Securities sold, not yet purchased, at fair value	4,730	438
Income taxes payable	11,509	11,460
Deferred taxes	368	719
Term debt	20,571	23,997
Total liabilities	1,965,948	1,506,955
Commitments and contingencies
Stockholders' Equity:
Preferred stock, $0.01 par value; 1,000,000 shares authorized; no shares issued or outstanding
Common stock, $0.01 par value; 100,000,000 shares authorized; 52,037,011 and 51,899,229 shares issued at September 30, 2012 and December 31, 2011, respectively	520	519
Additional paid-in capital	243,913	249,469
Retained earnings	411,938	653,344
Common stock held in treasury, at cost; 14,078,344 and 12,679,948 shares at September 30, 2012 and December 31, 2011, respectively	(249,555)	(240,559)
Accumulated other comprehensive income (net of tax)	11,832	8,341
Total stockholders' equity	418,648	671,114
Total liabilities and stockholders' equity	$ 2,384,596	$ 2,178,069