CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS UNAUDITED - USD ($)	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Operating activities
Net income	$ 63,257,000	$ 77,851,000
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Equity in net gains from partnerships	(681,000)	(572,000)
Depreciation and amortization	475,000	507,000
Stock based compensation expense	6,819,000	5,182,000
Deferred income taxes	(8,033,000)	(3,472,000)
Tax benefit from exercise of stock options	102,000	349,000
Foreign currency translation gain/(loss)	(22,000)	(15,000)
Other-than-temporary loss on available for sale securities	150,000	69,000
Fair value of donated securities	104,000	1,502,000
Gains on sales of available for sale securities	(30,000)	(3,511,000)
Accretion of zero coupon debentures	502,000	661,000
Loss on extinguishment of debt	310,000	84,000
(Increase) decrease in assets:
Investments in trading securities	29,096,000	(22,376,000)
Investments in partnerships:
Contributions to partnerships	(15,170,000)	(15,698,000)
Distributions from partnerships	22,800,000	4,828,000
Receivable from brokers	(24,745,000)	(30,424,000)
Investment advisory fees receivable	13,046,000	20,351,000
Income tax receivable and deferred tax assets	68,000	(1,988,000)
Other assets	20,402,000	563,000
Increase (decrease) in liabilities:
Payable to brokers	42,930,000	36,026,000
Income taxes payable and deferred tax liabilities	(5,019,000)	(4,950,000)
Compensation payable	48,768,000	58,873,000
Mandatorily redeemable noncontrolling interests	(45,000)	(51,000)
Accrued expenses and other liabilities	5,092,000	(1,639,000)
Total adjustments	136,919,000	44,299,000
Net cash provided by operating activities	200,176,000	122,150,000
Investing activities
Purchases of available for sale securities	(43,030,000)	(6,252,000)
Proceeds from sales of available for sale securities	1,064,000	8,018,000
Return of capital on available for sale securities	554,000	827,000
Net cash provided by investing activities	(41,412,000)	2,593,000
Financing activities
Contributions from redeemable noncontrolling interests	1,036,000	53,607,000
Redemptions of redeemable noncontrolling interests	(602,000)	(1,666,000)
Payments to Noncontrolling Interests	0	0
Proceeds from exercise of stock options	1,169,000	1,637,000
Repurchase of zero coupon subordinated debentures	(6,224,000)	(715,000)
Dividends paid	(5,252,000)	(4,567,000)
Purchase of treasury stock	(21,530,000)	(25,074,000)
Net cash provided used in financing activities	(31,403,000)	23,222,000
Effect of exchange rates on cash and cash equivalents	8,000	5,000
Net increase in cash and cash equivalents	127,369,000	147,970,000
Cash and cash equivalents at beginning of period	298,224,000	210,451,000
Increase in cash from consolidation	10,000	0
Increase in cash from deconsolidation	13,000	0
Cash and cash equivalents at end of period	425,616,000	358,421,000
Supplemental disclosures of cash flow information:
Cash paid for interest	3,897,000	3,847,000
Cash paid for taxes	$ 49,590,000	$ 52,956,000