Consolidated Company-Sponsored Investment Funds (Summary of Balance Sheet Amounts) (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016	Dec. 31, 2015
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and cash equivalents	$ 963,168	$ 994,510	$ 725,639	$ 577,300
Other assets	266,286	195,615
Total assets	9,067,912	8,740,448
Liabilities	4,800,837	4,279,300
Redeemable non-controlling interest	344,104	392,959
Partners' capital attributable to AB Unitholders	3,886,114	4,032,017
Non-redeemable non-controlling interests in consolidated entities	36,857	36,172
Total liabilities, redeemable non-controlling interest and capital	9,067,912	8,740,448
Company-sponsored investment funds
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and cash equivalents	364,777	337,525
Investments	659,336	574,076
Other assets	6,957	44,570
Liabilities	426,047	292,800
Redeemable non-controlling interest	335,440	384,294
Non-redeemable non-controlling interests in consolidated entities	36,168	34,622
Reportable entities | Company-sponsored investment funds
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and cash equivalents	364,777	337,525
Investments	659,336	574,076
Other assets	6,957	44,570
Total assets	1,031,070	956,171
Liabilities	426,047	292,800
Redeemable non-controlling interest	335,440	384,294
Partners' capital attributable to AB Unitholders	233,415	244,455
Non-redeemable non-controlling interests in consolidated entities	36,168	34,622
Total liabilities, redeemable non-controlling interest and capital	1,031,070	956,171
Reportable entities | VIEs
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and cash equivalents	364,738	337,525
Investments	629,680	550,850
Other assets	6,044	44,570
Total assets	1,000,462	932,945
Liabilities	416,194	292,800
Redeemable non-controlling interest	335,440	384,294
Partners' capital attributable to AB Unitholders	212,660	221,229
Non-redeemable non-controlling interests in consolidated entities	36,168	34,622
Total liabilities, redeemable non-controlling interest and capital	1,000,462	932,945
Reportable entities | VOEs
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and cash equivalents	39	0
Investments	29,656	23,226
Other assets	913	0
Total assets	30,608	23,226
Liabilities	9,853	0
Redeemable non-controlling interest	0	0
Partners' capital attributable to AB Unitholders	20,755	23,226
Non-redeemable non-controlling interests in consolidated entities	0	0
Total liabilities, redeemable non-controlling interest and capital	$ 30,608	$ 23,226