Long-term Incentive Compensation Plans - Unit Purchase Activity (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Share-based Payment Arrangement [Abstract]
Total amount of AB Holding Units Purchased (in units)	0.9	2.0
Total Cash Paid for AB Holding Units Purchased	$ 19.8	$ 58.6
Open Market Purchases of AB Holding Units Purchased (in units)	0.8	1.9
Total Cash Paid for Open Market Purchases of AB Holding Units	$ 17.3	$ 55.2

No definition available.

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The cash outflow to reacquire common and preferred stock.

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Number of shares purchased for issuance under share-based payment arrangement.

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- Definition

Number of shares that have been repurchased during the period and have not been retired and are not held in treasury. Some state laws may govern the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

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Equity impact of the value of stock that has been repurchased during the period and has not been retired and is not held in treasury. Some state laws may mandate the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

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