Long-term Incentive Compensation Plans	9 Months Ended
Sep. 30, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Long-term Incentive Compensation Plans	Long-term Incentive Compensation Plans AB maintains several unfunded, non-qualified long-term incentive compensation plans, under which the company grants awards of restricted AB Holding Units and options to buy AB Holding Units to its employees and members of the Board of Directors, who are not employed by AB or by any of AB’s affiliates (“Eligible Directors”). AB funds its restricted AB Holding Unit awards either by purchasing AB Holding Units on the open market or purchasing newly-issued AB Holding Units from AB Holding, and then keeping all of these AB Holding Units in a consolidated rabbi trust until delivering them or retiring them. In accordance with the AB Holding Partnership Agreement, when AB purchases newly-issued AB Holding Units from AB Holding, AB Holding is required to use the proceeds it receives from AB to purchase the equivalent number of newly-issued AB Units, thus increasing its percentage ownership interest in AB. AB Holding Units held in the consolidated rabbi trust are corporate assets in the name of the trust and are available to the general creditors of AB. During the three and nine months ended September 30, 2017, AB purchased 0.3 million and 5.9 million AB Holding Units for $6.9 million and $134.6 million, respectively (on a trade date basis). These amounts reflect open-market purchases of 0.3 million and 5.2 million AB Holding Units for $6.8 million and $117.1 million, respectively, with the remainder relating to purchases of AB Holding Units from employees to allow them to fulfill statutory tax withholding requirements at the time of delivery of long-term incentive compensation awards. During the three and nine months ended September 30, 2016, AB purchased 2.0 million and 5.8 million AB Holding Units for $45.2 million and $129.2 million, respectively (on a trade date basis). These amounts reflect open-market purchases of 2.0 million and 5.7 million AB Holding Units for $45.1 million and $127.1 million, respectively, with the remainder relating to purchases of AB Holding Units from employees to allow them to fulfill statutory tax withholding requirements at the time of delivery of long-term incentive compensation awards. Each quarter, AB considers whether to implement a plan to repurchase AB Holding Units pursuant to Rule 10b5-1 under the Securities Exchange Act of 1934, as amended (“Exchange Act”). A Rule 10b5-1 plan allows a company to repurchase its shares at times when it otherwise might be prevented from doing so because of self-imposed trading blackout periods or because it possesses material non-public information. Each broker selected by AB has the authority under the terms and limitations specified in the plan to repurchase AB Holding Units on AB’s behalf in accordance with the terms of the plan. Repurchases are subject to regulations promulgated by the SEC as well as certain price, market volume and timing constraints specified in the plan. The plan adopted during the second quarter of 2017 expired at the close of business on July 26, 2017. AB did not adopt a plan during the third quarter of 2017. AB may adopt additional Rule 10b5-1 plans in the future to engage in open-market purchases of AB Holding Units to help fund anticipated obligations under its incentive compensation award program and for other corporate purposes. During the first nine months of 2017 and 2016, AB granted to employees and Eligible Directors 2.2 million and 0.7 million restricted AB Holding Unit awards, respectively. AB used AB Holding Units repurchased during the period and newly-issued AB Holding Units to fund the restricted AB Holding Unit awards. During the first nine months of 2017 and 2016, AB Holding issued 1.0 million and 0.1 million AB Holding Units, respectively, upon exercise of options to buy AB Holding Units. AB Holding used the proceeds of $17.7 million and $2.4 million, respectively, received as payment in cash for the exercise price to purchase the equivalent number of newly-issued AB Units.

Long-term Incentive Compensation Plans

AB maintains several unfunded, non-qualified long-term incentive compensation plans, under which the company grants awards of restricted AB Holding Units and options to buy AB Holding Units to its employees and members of the Board of Directors, who are not employed by AB or by any of AB’s affiliates (“Eligible Directors”).

AB funds its restricted AB Holding Unit awards either by purchasing AB Holding Units on the open market or purchasing newly-issued AB Holding Units from AB Holding, and then keeping all of these AB Holding Units in a consolidated rabbi trust until delivering them or retiring them. In accordance with the AB Holding Partnership Agreement, when AB purchases newly-issued AB Holding Units from AB Holding, AB Holding is required to use the proceeds it receives from AB to purchase the equivalent number of newly-issued AB Units, thus increasing its percentage ownership interest in AB. AB Holding Units held in the consolidated rabbi trust are corporate assets in the name of the trust and are available to the general creditors of AB.

During the three and nine months ended September 30, 2017, AB purchased 0.3 million and 5.9 million AB Holding Units for $6.9 million and $134.6 million, respectively (on a trade date basis). These amounts reflect open-market purchases of 0.3 million and 5.2 million AB Holding Units for $6.8 million and $117.1 million, respectively, with the remainder relating to purchases of AB Holding Units from employees to allow them to fulfill statutory tax withholding requirements at the time of delivery of long-term incentive compensation awards. During the three and nine months ended September 30, 2016, AB purchased 2.0 million and 5.8 million AB Holding Units for $45.2 million and $129.2 million, respectively (on a trade date basis). These amounts reflect open-market purchases of 2.0 million and 5.7 million AB Holding Units for $45.1 million and $127.1 million, respectively, with the remainder relating to purchases of AB Holding Units from employees to allow them to fulfill statutory tax withholding requirements at the time of delivery of long-term incentive compensation awards.

Each quarter, AB considers whether to implement a plan to repurchase AB Holding Units pursuant to Rule 10b5-1 under the Securities Exchange Act of 1934, as amended (“Exchange Act”). A Rule 10b5-1 plan allows a company to repurchase its shares at times when it otherwise might be prevented from doing so because of self-imposed trading blackout periods or because it possesses material non-public information. Each broker selected by AB has the authority under the terms and limitations specified in the plan to repurchase AB Holding Units on AB’s behalf in accordance with the terms of the plan. Repurchases are subject to regulations promulgated by the SEC as well as certain price, market volume and timing constraints specified in the plan. The plan adopted during the second quarter of 2017 expired at the close of business on July 26, 2017. AB did not adopt a plan during the third quarter of 2017. AB may adopt additional Rule 10b5-1 plans in the future to engage in open-market purchases of AB Holding Units to help fund anticipated obligations under its incentive compensation award program and for other corporate purposes.

During the first nine months of 2017 and 2016, AB granted to employees and Eligible Directors 2.2 million and 0.7 million restricted AB Holding Unit awards, respectively. AB used AB Holding Units repurchased during the period and newly-issued AB Holding Units to fund the restricted AB Holding Unit awards.

During the first nine months of 2017 and 2016, AB Holding issued 1.0 million and 0.1 million AB Holding Units, respectively, upon exercise of options to buy AB Holding Units. AB Holding used the proceeds of $17.7 million and $2.4 million, respectively, received as payment in cash for the exercise price to purchase the equivalent number of newly-issued AB Units.