Fair Value Fair Value (Private Equity Level 3 Fair Value Measurements) (Details) - Private Equity Technology Media and Telecommunications - Recurring - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
Sep. 30, 2015	Dec. 31, 2014
Quantitative information about Level 3 fair value measurements [Abstract]
Fair value	$ 10,115	$ 20,112
Marketability discount	30.00%
Discount rate		18.00%
Discount years		2 years
Minimum
Quantitative information about Level 3 fair value measurements [Abstract]
Revenue multiple	2.1	2.0
Maximum
Quantitative information about Level 3 fair value measurements [Abstract]
Revenue multiple	5.3	3.5

The number of years of discount valuation used to estimate fair value of investment.

No definition available.

Name:	ablp_FairValueValuationDiscountYears
Namespace Prefix:	ablp_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

This element represents the aggregate of the assets reported on the balance sheet at period end measured at fair value on a recurring basis by the entity. This element is intended to be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements.

+ References

No definition available.

+ Details

Name:	us-gaap_AssetsFairValueDisclosureRecurring
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Adjustment to the discount rate used to measure fair value for lack of ability to convert business interests into cash quickly.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (bbb)

-URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258

+ Details

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Namespace Prefix:	us-gaap_
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Balance Type:	na
Period Type:	duration

- Definition

Interest rate used to find the present value of an amount to be paid or received in the future as an input to measure fair value. For example, but not limited to, weighted average cost of capital (WACC), cost of capital, cost of equity and cost of debt.

+ References

+ Details

Name:	us-gaap_FairValueInputsDiscountRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- References

No definition available.

+ Details

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- Definition

Market valuation of entity divided by revenue, used as an input to measure fair value.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

- Details

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- Details

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- Details

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- Details

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