Consolidated Company-Sponsored Investment Funds (Summary of Balance Sheet Amounts) (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2015
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and cash equivalents	$ 1,064,877	$ 994,510	$ 829,233	$ 577,300
Other assets	229,058	195,615
Total assets	9,482,404	8,740,448
Liabilities	5,079,930	4,279,300
Redeemable non-controlling interest	403,609	392,959
Partners' capital attributable to AB Unitholders	3,964,122	4,032,017
Non-redeemable non-controlling interests in consolidated entities	34,743	36,172
Total liabilities, redeemable non-controlling interest and capital	9,482,404	8,740,448
Consolidated Investment Portfolios [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and cash equivalents	326,643	337,525
Investments	754,422	574,076
Other assets	13,836	44,570
Liabilities	398,137	292,800
Redeemable non-controlling interest	394,944	384,294
Non-redeemable non-controlling interests in consolidated entities	32,970	34,622
Reportable entities | Consolidated Investment Portfolios [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and cash equivalents	326,643	337,525
Investments	754,422	574,076
Other assets	13,836	44,570
Total assets	1,094,901	956,171
Liabilities	398,137	292,800
Redeemable non-controlling interest	394,944	384,294
Partners' capital attributable to AB Unitholders	268,850	244,455
Non-redeemable non-controlling interests in consolidated entities	32,970	34,622
Total liabilities, redeemable non-controlling interest and capital	1,094,901	956,171
Reportable entities | VIEs
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and cash equivalents	326,324	337,525
Investments	730,533	550,850
Other assets	13,571	44,570
Total assets	1,070,428	932,945
Liabilities	398,108	292,800
Redeemable non-controlling interest	394,937	384,294
Partners' capital attributable to AB Unitholders	244,413	221,229
Non-redeemable non-controlling interests in consolidated entities	32,970	34,622
Total liabilities, redeemable non-controlling interest and capital	1,070,428	932,945
Reportable entities | VOEs
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and cash equivalents	319	0
Investments	23,889	23,226
Other assets	265	0
Total assets	24,473	23,226
Liabilities	29	0
Redeemable non-controlling interest	7	0
Partners' capital attributable to AB Unitholders	24,437	23,226
Non-redeemable non-controlling interests in consolidated entities	0	0
Total liabilities, redeemable non-controlling interest and capital	$ 24,473	$ 23,226