Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Mar. 31, 2020	Dec. 31, 2019
Cash Flows from Operating Activities:
Net income (loss)	$ 1,006	$ 22,468
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation expense, intangible asset and other amortization	10,878	9,874
Stock-based compensation	3,621	5,629
Amortization of deferred commissions	517	980
Payments of deferred commissions	(518)	(455)
Equity in earnings of equity method investments	(657)	(496)
(Gain) Loss on extinguishment of debt	(705)	0
Sales (purchases) of investments, net	2,153	9,413
Deferred taxes, net	7,175	(1,705)
Changes in operating assets and liabilities:
Accounts receivable, net and other assets	6,377	(2,732)
Accrued compensation and benefits, accounts payable, accrued liabilities and other liabilities	(64,917)	(60,857)
Operating activities of consolidated investment products (CIP):
Net cash provided by (used in) operating activities	(252,320)	(23,215)
Cash Flows from Investing Activities:
Capital expenditures and other asset purchases	(358)	(2,568)
Sale of available-for-sale securities	0	2,044
Net cash provided by (used in) investing activities	9,366	(2,095)
Cash Flows from Financing Activities:
Payment of long term debt	(26,547)	(12,413)
Common stock dividends paid	(5,832)	(4,441)
Preferred stock dividends paid	(2,084)	(2,084)
Repurchases of common shares	(10,000)	(14,999)
Proceeds from exercise of stock options	101	449
Taxes paid related to net share settlement of restricted stock units	(3,551)	(4,804)
Net subscriptions received from (redemptions/distributions paid to) noncontrolling interests	728	6,012
Net cash provided by (used in) financing activities	314,641	(31,280)
Net increase (decrease) in cash, cash equivalents and restricted cash	71,687	(56,590)
Cash, cash equivalents and restricted cash, beginning of period	321,939	254,656	$ 254,656
Cash, cash equivalents and restricted cash, end of period	393,626	198,066	321,939
Non-Cash Investing Activities:
Change in accrual for capital expenditures	(20)	(1,267)
Non-Cash Financing Activities:
Increase (decrease) to noncontrolling interests due to consolidation (deconsolidation) of CIP, net	17,137	(6,423)
Common stock dividends payable	5,175	3,865
Preferred stock dividends payable	0	2,084
Conversion of preferred stock to common stock	115,000	0
Reconciliation of cash, cash equivalents and restricted cash
Cash, cash equivalents and restricted cash at end of period	321,939	198,066	$ 321,939	$ 393,626	$ 321,939
Consolidated entity excluding consolidated investment products
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Realized and unrealized (gains) losses on investments, net	7,544	(3,292)
Reconciliation of cash, cash equivalents and restricted cash
Cash and cash equivalents				158,456	221,781
Consolidated Investment Products
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Realized and unrealized (gains) losses on investments, net	6,581	1,497
Operating activities of consolidated investment products (CIP):
Purchases of investments by CIP	(509,337)	(157,158)
Sales of investments by CIP	273,962	152,572
Net proceeds (purchases) of short term investments by CIP	(396)	(911)
(Purchases) sales of securities sold short by CIP, net	181	1,064
Change in other assets of CIP	(17)	578
Change in liabilities of CIP	932	316
Amortization of discount on notes payable of CIP	3,300	0
Cash Flows from Investing Activities:
Change in cash and cash equivalents of CIP due to consolidation (deconsolidation), net	9,724	(1,571)
Cash Flows from Financing Activities:
Payments on borrowings by CIP	(40,690)	0
Borrowings by CIP	$ 402,516	$ 1,000
Reconciliation of cash, cash equivalents and restricted cash
Cash and cash equivalents				227,941	99,691
Cash pledged or on deposit of CIP				$ 7,229	$ 467