Condensed Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Cash flows from operating activities:
Net income	$ 163,178	$ 142,744
Adjustments to reconcile net income to net cash provided by operating activities:
Amortization of deferred sales commissions	11,242	12,399
Non-cash long-term incentive compensation expense	739	3,387
Depreciation and other amortization	14,784	14,294
Unrealized gains on investments	(10,587)	(7,541)
Other, net	11,936	578
Changes in assets and liabilities:
(Increase) in segregated cash and securities	(158,502)	(43,862)
Decrease (increase) in receivables	117,443	(125,720)
(Increase) decrease in investments	127,820	42,310
Decrease (increase) in deferred sales commissions	2,007	(15,991)
(Increase) decrease in other assets	(1,402)	(18,756)
Increase in payables	277,154	181,581
Increase in accounts payable and accrued expenses	62,805	988
Increase in accrued compensation and benefits	59,741	73,370
Net cash provided by operating activities	675,917	259,781
Cash flows from investing activities:
Purchases of investments	0	(85)
Proceeds from sales of investments	91	0
Purchases of furniture, equipment and leasehold improvements	(11,241)	(5,050)
Proceeds from sales of furniture, equipment and leasehold improvements	0	33
Net cash used in investing activities	(11,150)	(5,102)
Cash flows from financing activities:
(Repayment) issuance of commercial paper, net	(96,989)	11,295
(Decrease) increase in overdrafts payable	(91,313)	38,772
Distributions to General Partner and Unitholders	(153,433)	(173,075)
Capital contributions from (distributions to) non-controlling interests in consolidated entities	0	202
Capital contributions from General Partner	233	335
Capital contributions from AB Holding	6,115	6,019
Payments of contingent payment arrangements	(280)	(213)
Additional investments by AB Holding with proceeds from exercise of compensatory options to buy AB Holding Units	1,457	3,901
Purchases of AB Holding Units to fund long-term incentive compensation plan awards, net	(39,550)	(16,929)
Purchases of AB Units	(4)	(11)
Other	(2)	(7)
Net cash used in financing activities	(421,274)	(129,711)
Effect of exchange rate changes on cash and cash equivalents	8,440	(9,183)
Net increase in cash and cash equivalents	251,933	115,785
Cash and cash equivalents as of beginning of the period	577,300	555,503
Cash and cash equivalents as of end of the period	829,233	671,288
Consolidated Variable Interest Entities
Adjustments to reconcile net income to net cash provided by operating activities:
Unrealized gains on investments	8,032	0
Changes in assets and liabilities:
(Increase) decrease in investments	(12,208)	0
(Increase) decrease in other assets	1,735	0
Cash flows from financing activities:
Capital contributions from (distributions to) non-controlling interests in consolidated entities	(47,508)	$ 0
Cash and cash equivalents as of beginning of the period	0
Cash and cash equivalents as of end of the period	32,855
Supplemental information - consolidation of variable interest entities:
Consolidation of cash and cash equivalents of consolidated variable interest entities	35,817
Consolidation of investments of consolidated variable interest entities	215,175
Consolidation of other assets of consolidated variable interest entities	13,871
Consolidation of other liabilities of consolidated variable interest entities	14,012
Consolidation of redeemable non-controlling interest of consolidated variable interest entities	$ 250,851