Condensed Consolidated Statements of Financial Condition (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Assets
Cash and cash equivalents	$ 261,567	$ 245,875
Cash restricted or segregated under regulations and other	70,275	61,117
Deposits with clearing organizations	32,476	29,149
Securities owned, at fair value	12,197	10,086
Receivables from brokers, dealers and clearing organizations	1,644,884	1,107,119
Receivables from customers	942,250	546,825
Premises and equipment, net	67,845	54,989
Capitalized software, net	39,418	43,994
Other intangibles, net	32,159	35,227
Income taxes receivable	275	7,460
Deferred taxes	36,061	39,155
Other assets	17,903	15,763
Total assets	3,157,310	2,196,759
Liabilities:
Accounts payable and accrued expenses	177,609	165,062
Short-term bank loans	52,486	22,154
Payables to brokers, dealers and clearing organizations	1,522,443	1,337,459
Payables to customers	936,381	226,892
Securities sold, not yet purchased, at fair value	7,490	5,249
Income taxes payable	17,450	10,608
Deferred taxes	343	293
Term debt	33,319	19,272
Total liabilities	2,747,521	1,786,989
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; 52,158,374 and 52,037,011 shares issued at September 30, 2013 and December 31, 2012, respectively	522	520
Additional paid-in capital	238,852	245,002
Retained earnings	426,908	405,485
Common stock held in treasury, at cost; 15,879,299 and 14,677,872 shares at September 30, 2013 and December 31, 2012, respectively	(265,522)	(253,111)
Accumulated other comprehensive income (net of tax)	9,029	11,874
Total stockholders' equity	409,789	409,770
Total liabilities and stockholders' equity	$ 3,157,310	$ 2,196,759