Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash flows from operating activities:
Net income	$ 694,846	$ 586,302	$ 564,317
Adjustments to reconcile net income to net cash provided by operating activities:
Amortization of deferred sales commissions	41,066	49,145	41,508
Non-cash long-term incentive compensation expense	152,162	176,160	176,636
Depreciation and other amortization	59,026	56,426	62,515
Unrealized (gains) losses on investments	(26,285)	29,281	13,343
Losses on real estate asset write-offs	5,456	0	429
Other, net	3,629	(2,888)	(1,819)
Changes in assets and liabilities:
(Increase) decrease in segregated cash and securities	(380,823)	(88,997)	504,307
(Increase) in receivables	(295,677)	(121,985)	(444,536)
Decrease in investments	162,607	58,053	3,563
(Increase) in deferred sales commissions	(5,886)	(29,925)	(89,224)
Decrease (increase) in other assets	12,961	(42,690)	(6,375)
Increase (decrease) in payables	886,520	65,309	(85,226)
Increase (decrease) in accounts payable and accrued expenses	2,459	(32,372)	(58,066)
(Decrease) in accrued compensation and benefits	(3,238)	(34,645)	(51,283)
Net cash provided by operating activities	1,548,048	667,174	630,089
Cash flows from investing activities:
Purchases of investments	0	(168)	(492)
Proceeds from sales of investments	372	4,240	140
Purchases of furniture, equipment and leasehold improvements	(36,728)	(30,217)	(25,433)
Proceeds from sales of furniture, equipment and leasehold improvements	15	2	176
Purchase of intangible asset	(2,500)	0	0
Purchase of businesses, net of cash acquired	(20,541)	0	(60,610)
Net cash used in investing activities	(59,382)	(26,143)	(86,219)
Cash flows from financing activities:
(Repayment) issuance of commercial paper, net	(72,003)	93,867	219,818
(Decrease) increase in overdrafts payable	(84,512)	79,540	(38,967)
Distributions to General Partner and Unitholders	(537,564)	(597,872)	(572,348)
Redemptions of non-controlling interests of consolidated VIEs, net	364	(12,165)	(12,199)
Capital contributions from affiliates	1,000	2,041	511
Payments of contingent payment arrangements/purchase of shares	(1,006)	(5,027)	(759)
Additional investments by AB Holding with proceeds from exercise of compensatory options to buy AB Holding Units	6,108	9,233	18,955
Purchases of AB Holding Units to fund long-term incentive compensation plan awards, net	(235,893)	(213,484)	(90,143)
Purchases of AB Units	(374)	(805)	(1,553)
Other	(22)	(26)	(1,546)
Net cash used in financing activities	(1,061,278)	(644,698)	(478,231)
Effect of exchange rate changes on cash and cash equivalents	(10,178)	(10,353)	(20,027)
Net increase (decrease) in cash and cash equivalents	417,210	(14,020)	45,612
Cash and cash equivalents as of beginning of the period	541,483	555,503	509,891
Cash and cash Equivalents		577,300
Cash and cash equivalents as of end of the period	994,510	541,483	555,503
Cash paid:
Interest paid	11,148	3,984	3,148
Income taxes paid	27,387	25,999	42,028
Non-cash investing activities:
Fair value of assets acquired	33,583	0	87,821
Fair value of liabilities assumed	1,149	0	1,342
Fair value of redeemable non-controlling interest recorded	0	0	16,504
Non-cash financing activities:
Payables recorded under contingent payment arrangements	11,893	0	9,365
VIEs Consolidated [Member]
Adjustments to reconcile net income to net cash provided by operating activities:
Unrealized (gains) losses on investments	(31,040)	0	0
Changes in assets and liabilities:
Consolidation of cash and cash equivalents of consolidated variable interest entities, net	358,534	0	0
Decrease in investments	(320,993)	0	0
Decrease (increase) in other assets	232,724	0	0
Cash flows from financing activities:
Redemptions of non-controlling interests of consolidated VIEs, net	(137,376)	0	$ 0
Cash and cash equivalents as of beginning of the period	0
Cash and cash equivalents as of end of the period	$ 337,525	$ 0