Long-term Incentive Compensation Plans (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
AB Holding Units purchased (in units)	1,900,000	100,000	3,800,000	800,000
Amount paid for AB Holding Units acquired	$ 44,300	$ 4,300	$ 84,000	$ 21,300
Open-market purchases of AB Holding Units (in units)	1,900,000	100,000	3,700,000	700,000
Amount paid for open-market purchases of AB Holding Units	$ 43,900	$ 4,000	$ 82,000	$ 19,000
Restricted AB Holding Units awarded to employees (in units)			300,000	300,000
Units issued upon exercise of options (in units)			139,093	500,000
Proceeds from stock options exercised			$ 2,377	$ 8,979