Long-term Incentive Compensation Plans (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
AB Holding Units purchased (in units)	2,000,000	3,000,000	5,800,000	3,800,000
Amount paid for AB Holding Units acquired	$ 45,200	$ 82,100	$ 129,200	$ 103,400
Open-market purchases of AB Holding Units (in units)	2,000,000	3,000,000	5,700,000	3,700,000
Amount paid for open-market purchases of AB Holding Units	$ 45,100	$ 82,100	$ 127,100	$ 101,100
Restricted AB Holding Units awarded to employees (in units)			700,000	300,000
Units issued upon exercise of options (in units)			139,093	500,000
Proceeds from stock options exercised			$ 2,371	$ 8,979