Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Cash flows from operating activities:
Net income	$ 156,255	$ 160,536
Adjustments to reconcile net income to net cash provided by operating activities:
Amortization of deferred sales commissions	9,079	11,242
Non-cash long-term incentive compensation expense	7,693	739
Depreciation and other amortization	16,282	14,784
Unrealized (gains) losses on investments	(16,397)	(10,587)
Other, net	3,528	11,936
Changes in assets and liabilities:
(Increase) in segregated cash and securities	(309,729)	(158,502)
(Increase) decrease in receivables	(206,909)	117,443
Decrease (increase) in investments	20,497	127,820
Decrease in deferred sales commissions	821	2,007
(Increase) decrease in other assets	(32,109)	(1,402)
Increase in payables	502,976	277,154
(Decrease) increase in accounts payable and accrued expenses	(30,810)	65,447
Increase in accrued compensation and benefits	80,054	59,741
Net cash provided by operating activities	156,956	675,917
Cash flows from investing activities:
Proceeds from sales of investments	0	91
Purchases of furniture, equipment and leasehold improvements	(6,525)	(11,241)
Net cash used in investing activities	(6,525)	(11,150)
Cash flows from financing activities:
Issuance (repayment) of commercial paper, net	93,581	(96,989)
Increase (decrease) in overdrafts payable	50,377	(91,313)
Distributions to General Partner and Unitholders	(198,040)	(153,433)
Capital contributions/Redemptions of non-controlling interests of consolidated company-sponsored investment funds, net	(3,137)	0
Capital contributions (to) from affiliates	(81)	6,348
Payments of contingent payment arrangements	(412)	(280)
Additional investments by AB Holding with proceeds from exercise of compensatory options to buy AB Holding Units	4,468	1,457
Purchases of AB Holding Units to fund long-term incentive compensation plan awards, net	(30,833)	(39,550)
Other	0	(6)
Net cash used in financing activities	(88,113)	(421,274)
Effect of exchange rate changes on cash and cash equivalents	8,049	8,440
Net increase in cash and cash equivalents	70,367	251,933
Cash and cash equivalents as of beginning of the period	994,510	577,300
Cash and cash equivalents as of end of the period	1,064,877	829,233
Consolidated Investment Portfolios [Member]
Adjustments to reconcile net income to net cash provided by operating activities:
Unrealized (gains) losses on investments	(26,834)	8,032
Changes in assets and liabilities:
Decrease (increase) in investments	(153,512)	(12,208)
(Increase) decrease in other assets	136,071	1,735
Cash flows from financing activities:
Capital contributions/Redemptions of non-controlling interests of consolidated company-sponsored investment funds, net	(4,036)	$ (47,508)
Cash and cash equivalents as of beginning of the period	337,525
Cash and cash equivalents as of end of the period	$ 326,643