Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash flows from operating activities:
Net income	$ 1,153,734	$ 861,783	$ 781,683
Adjustments to reconcile net income to net cash provided by operating activities:
Amortization of deferred sales commissions	34,364	27,355	15,029
Non-cash long-term incentive compensation expense	216,425	195,642	208,182
Depreciation and other amortization	44,985	61,028	77,021
Unrealized losses (gains) on investments	4,454	10,405	(13,431)
Non-cash lease expense	98,773	98,798	103,773
Other, net	22,580	(2,914)	10,281
Changes in assets and liabilities:
Decrease (increase) in securities, segregated	249,521	(658,612)	74,688
(Increase) decrease in receivables	(360,789)	(182,684)	223,137
(Increase) decrease in investments	(27,000)	7,597	460,347
(Increase) in deferred sales commissions	(45,197)	(55,125)	(34,177)
(Increase) decrease in other assets	(6,578)	69,160	(23,140)
Increase (decrease) in payables	214,139	861,502	(641,369)
Increase (decrease) in accounts payable and accrued expenses	35,877	10,666	(56,518)
Increase (decrease) in accrued compensation and benefits	50,545	46,885	(7,486)
Operating cash flows from operating leases	(114,769)	(115,656)	(132,669)
Net cash provided by operating activities	1,298,782	1,521,421	827,480
Cash flows from investing activities:
Purchases of equity method investments	0	(4,079)	0
Purchases of furniture, equipment and leasehold improvements	(61,931)	(41,504)	(28,303)
Acquisition of businesses, net of cash acquired	(3,793)	(13,552)	5,255
Net cash used in investing activities	(65,724)	(59,135)	(23,048)
Cash flows from financing activities:
Proceeds from debt, net	80,000	115,000	2,105
Increase (decrease) in overdrafts payable	16,192	(12,633)	(59,924)
Distributions to General Partner and Unitholders	(1,059,892)	(836,879)	(703,512)
Capital contributions (to) from affiliates	(2,346)	(867)
Capital contributions (to) from affiliates			269
Additional investments by AB Holding with proceeds from exercise of compensatory options to buy AB Holding Units	3,402	147	11,511
Purchases of AB Holding Units to fund long-term incentive compensation plan awards, net	(261,825)	(148,624)	(171,930)
Other, net	(2,186)	306	(3,571)
Net cash used in financing activities	(912,956)	(1,102,583)	(774,961)
Effect of exchange rate changes on cash and cash equivalents	(17,982)	23,032	8,376
Net increase in cash and cash equivalents	302,120	382,735	37,847
Cash and cash equivalents as of beginning of the period	1,073,906	691,171	653,324
Cash and cash equivalents as of end of the period	1,376,026	1,073,906	691,171
Cash paid:
Interest paid	5,263	18,858	66,002
Income taxes paid	55,656	59,791	52,444
Non-cash investing activities:
Fair value of assets acquired (excluding cash acquired of $2.8 million, $0.6 million and $11.8 million, for 2021, 2020 and 2019, respectively)	13,235	18,389	28,966
Fair value of liabilities assumed	1,642	437	16,837
Non-cash financing activities:
Payables recorded under contingent payment arrangements	7,800	4,400	17,384
Consolidated company-sponsored investment funds
Adjustments to reconcile net income to net cash provided by operating activities:
Unrealized losses (gains) on investments	1,882	(854)	(36,150)
Changes in assets and liabilities:
(Increase) decrease in investments	(312,325)	279,276	(193,158)
(Increase) decrease in other assets	38,161	7,169	11,437
Cash flows from financing activities:
Subscriptions (redemptions) of non-controlling interests of consolidated company-sponsored investment funds, net	$ 313,699	$ (219,033)	$ 150,091