Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Activities
Net Income Including the Noncontrolling Interests in Subsidiaries	$ 222,299	$ 294,901	$ 221,514
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities
Amortization of Deferred Sales Commissions	2,967	8,025	11,980
Depreciation and Other Amortization	17,087	10,637	9,578
Share-Based Compensation Expense	23,893	22,508	22,445
(Gain) Loss on Disposal of Assets	298	(7,193)	1,070
Provision (Benefit) for Deferred Income Taxes	12,257	(59,272)	17,496
Net Unrealized Loss (Gain) on Investments	4,322	(889)	(4,624)
Net Sales of Investments—Consolidated Investment Companies	16,696	133,992	4,746
Adoption of New Accounting Pronouncement	0	0	(2,653)
Deferred Sales Commissions Paid	(43)	(4,715)	(11,801)
Contingent Deferred Sales Charges Received	0	1,785	2,195
Distributions from Equity Investments	1,173	0	0
Other Changes in Assets and Liabilities:
Increase in Receivables, net	(11,080)	(7,914)	(11,044)
(Increase) Decrease in Prepaid Expenses and Other Assets	4,029	(115)	1,114
(Decrease) Increase in Accounts Payable and Accrued Expenses	(96,188)	(9,160)	6,001
Increase (Decrease) in Other Liabilities	8,572	4,785	(2,346)
Net Cash Provided by Operating Activities	206,282	387,375	265,671
Investing Activities
Purchases of Investments—Affiliates and Other	(7,267)	(5,779)	(24,153)
Cash Paid for Business Acquisitions, net of Cash Acquired	(170,392)	(4,352)	0
Proceeds from Redemptions of Investments—Affiliates and Other	20,283	20,930	15,953
Cash Paid for Property and Equipment	(17,274)	(9,799)	(12,839)
Distribution from Equity Investment	211	0	0
Net Cash (Used) Provided by Investing Activities	(174,439)	1,000	(21,039)
Financing Activities
Dividends Paid	(106,943)	(101,511)	(205,468)
Purchases of Treasury Stock	(29,247)	(48,642)	(81,771)
Distributions to Noncontrolling Interests in Subsidiaries	(18,492)	(10,337)	(18,291)
Contributions from Noncontrolling Interests in Subsidiaries	2,801	4,687	17,868
Proceeds from Shareholders for Share-Based Compensation	1,444	1,299	1,436
Proceeds from New Borrowings	87,650	0	0
Payments on Debt	(122,650)	(21,250)	(25,500)
Other Financing Activities	(678)	(1,167)	(640)
Net Cash Used by Financing Activities	(186,115)	(176,921)	(312,366)
Effect of Exchange Rates on Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents	(5,111)	0	0
Net (Decrease) Increase in Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	(159,383)	211,454	(67,734)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Beginning of Period	316,809	105,355	173,089
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, End of Period	157,426	316,809	105,355
Less: Restricted Cash and Restricted Cash Equivalents Recorded in Other Long-Term Assets	594	545	516
Cash and Cash Equivalents	156,832	316,264	104,839
Cash paid during the year for:
Income taxes	61,573	118,412	104,581
Interest	$ 5,320	$ 4,109	$ 3,487