CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Operating activities
Net income	$ 117,365,000	$ 75,595,000	$ 69,675,000
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Equity in net gains from partnerships	(5,748,000)	(5,948,000)	(1,060,000)
Depreciation and amortization	766,000	777,000	825,000
Stock based compensation expense	2,072,000	13,583,000	2,588,000
Deferred income taxes	6,557,000	8,504,000	(1,521,000)
Tax benefit from exercise of stock options	16,000	105,000	0
Foreign currency translation gain/(loss)	20,000	(28,000)	8,000
Other-than-temporary loss on available for sale securities	97,000	20,000	0
Donated securities	1,931,000	448,000	167,000
Gains on sales of available for sale securities	(17,688,000)	(1,565,000)	(772,000)
Accretion of zero coupon debentures	1,253,000	3,155,000	4,572,000
(Gain) loss on extinguishment of debt	998,000	6,307,000	(2,000)
(Increase) decrease in assets:
Investments in trading securities	101,000	17,174,000	(58,286,000)
Investments in partnerships:
Contributions to partnerships	(12,257,000)	(27,443,000)	(15,483,000)
Distributions from partnerships	19,562,000	36,735,000	57,148,000
Receivable from brokers	1,194,000	(29,742,000)	(30,039,000)
Investment advisory fees receivable	(9,078,000)	(10,272,000)	12,718,000
Income tax receivable and deferred tax assets	573,000	(979,000)	286,000
Other assets	641,000	338,000	(5,659,000)
Increase (decrease) in liabilities:
Payable to brokers	(3,581,000)	3,576,000	9,216,000
Income taxes payable and deferred tax liabilities	5,590,000	432,000	(4,456,000)
Compensation payable	24,128,000	(7,162,000)	(6,076,000)
Mandatorily redeemable noncontrolling interests	13,000	(44,000)	(137,000)
Accrued expenses and other liabilities	6,471,000	2,179,000	2,651,000
Total adjustments	23,631,000	10,150,000	(33,312,000)
Net cash provided by operating activities	140,996,000	85,745,000	36,363,000
Investing activities
Purchases of available for sale securities	(9,080,000)	(1,268,000)	(4,378,000)
Proceeds from sales of available for sale securities	37,888,000	3,184,000	6,054,000
Return of capital on available for sale securities	1,459,000	2,531,000	2,306,000
Net cash provided by investing activities	30,267,000	4,447,000	3,982,000
Financing activities
Contributions from redeemable noncontrolling interests	5,150,000	24,189,000	22,418,000
Redemptions of redeemable noncontrolling interests	(16,223,000)	(13,069,000)	(2,340,000)
Issuance of 5.875% Senior notes due June 1, 2021	0	0	100,000,000
Issuance costs on the 5.875% Senior notes due June 1, 2021	0	0	(934,000)
Repayment of 5.5% Convertible note due May 15, 2013	(99,000,000)	0	0
Redemptions of noncontrolling interests	(524,000)	0
Repurchase of Zero coupon subordinated debentures due December 31, 2015	(7,705,000)	(56,215,000)	(32,000)
Proceeds from exercise of stock options	76,000	920,000	0
Dividends paid	(18,419,000)	(76,809,000)	(30,477,000)
Payments to Noncontrolling Interests	0	0	(331,000)
Purchase of treasury stock	(14,768,000)	(54,928,000)	(20,408,000)
Net cash (used in) provided by financing activities	(151,413,000)	(175,912,000)	67,896,000
Effect of exchange rates on cash and cash equivalents	(7,000)	(12,000)	0
Net increase in cash and cash equivalents	19,843,000	(85,732,000)	108,241,000
Cash and cash equivalents at beginning of period	190,608,000	276,340,000	169,601,000
Decrease in cash from deconsolidation of partnership	0	0	1,502,000
Cash and cash equivalents at end of period	210,451,000	190,608,000	276,340,000
Supplemental disclosures of cash flow information:
Cash paid for interest	9,797,000	10,049,000	9,539,000
Cash paid for taxes	$ 51,964,000	$ 32,106,000	$ 45,460,000