Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Cash flows from operating activities:
Net income	$ 333,239	$ 388,772
Adjustments to reconcile net income to net cash provided by operating activities:
Amortization of deferred sales commissions	6,743	12,711
Non-cash long-term incentive compensation expense	27,307	14,825
Depreciation and other amortization	83,997	35,626
Unrealized (gains) losses on investments	(16,724)	(3,257)
Other, net	11,537	(1,907)
Changes in assets and liabilities:
Decrease (increase) in segregated cash and securities	59,965	(472,517)
Decrease (increase) in receivables	43,325	(220,343)
Decrease (increase) in investments	506,061	(59,219)
(Increase) decrease in deferred sales commissions	(10,309)	653
(Increase) in right-of-use assets	(577,992)
(Increase) decrease in other assets	(4,515)	(108,751)
(Decrease) increase in payables	(440,029)	682,703
(Decrease) in accounts payable and accrued expenses	516,918
(Decrease) in accounts payable and accrued expenses	(61,705)	(10,141)
Increase in accrued compensation and benefits	180,701	225,571
Net cash provided by operating activities	546,974	765,474
Cash flows from investing activities:
Purchases of furniture, equipment and leasehold improvements	(11,276)	(11,458)
Acquisition of business, net of cash acquired	5,255	0
Net cash used in investing activities	(6,021)	(11,458)
Cash flows from financing activities:
(Repayment) issuance of commercial paper, net	(85,888)	20,058
Repayment of bank loans	(25,000)	(75,000)
(Decrease) in overdrafts payable	(19,144)	(28,952)
Distributions to General Partner and Unitholders	(343,471)	(466,522)
Capital contributions from (to) affiliates	495	(1,178)
Additional investments by AB Holding with proceeds from exercise of compensatory options to buy AB Holding Units	8,951	8,340
Purchases of AB Holding Units to fund long-term incentive compensation plan awards, net	(58,358)	(34,864)
Other	291	0
Net cash used in financing activities	(473,098)	(1,093,974)
Effect of exchange rate changes on cash and cash equivalents	(179)	(6,039)
Net increase (decrease) in cash and cash equivalents	67,676	(345,997)
Cash and cash equivalents as of beginning of the period	653,324	998,448
Cash and cash equivalents as of end of the period	721,000	652,451
Non-cash investing activities:
Fair value of assets acquired (excluding cash acquired of $11.8 million)	28,966	0
Fair value of liabilities assumed	16,837	0
Non-cash financing activities:
Payables recorded under contingent payment arrangements	17,384	0
Company-sponsored investment funds
Adjustments to reconcile net income to net cash provided by operating activities:
Unrealized (gains) losses on investments	(32,173)	(20,463)
Changes in assets and liabilities:
Decrease (increase) in investments	(86,566)	965,121
(Increase) decrease in other assets	7,194	(663,910)
Cash flows from financing activities:
Subscriptions (redemptions) of investments in consolidated company-sponsored investment funds, net	$ 49,026	$ (515,856)