SHARE-BASED COMPENSATION PROGRAMS - Schedule of Compensation Costs (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation costs	$ 14,043	$ 11,176
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation costs	2,598	3,402
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation costs	(920)	9
AB Restricted Units | Alliance Bernstein
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation costs	12,484	7,700
Other compensation plans | Parent Company
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation costs	$ (119)	$ 65