Long-term Incentive Compensation Plans (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Employee allocation percentage maximum (in hundredths)	50.00%
Long-term incentive cash maximum per employee	$ 250,000
Long-term incentive awards vesting period	4 years
Period over which holding units are typically distributed to directors	3 years
AB Holding Units purchased in periods (in units)	700,000	200,000
Dollar amount paid for AB Holding Units acquired	17,000,000	3,700,000
Open-market purchases of AB Holding Units (in units)	600,000
Dollar amount paid for open-market purchases of AB Holding Units	15,100,000
Restricted AB Holding Units awarded to employees (in units)	100,000	200,000
Units issued upon exercise of options (in units)	228,816
Proceeds from stock options exercised	3,901,000	4,656,000
Employees Based Outside of the United States [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Employee allocation percentage maximum (in hundredths)	100.00%
Long-term incentive cash maximum per employee	$ 100,000