LONG-TERM INCENTIVE COMPENSATION (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Long-term incentive compensation expense
Long-term incentive awards granted	$ 0.2		$ 77.5
Vesting period			4 years
Total long-term incentive compensation	17.6	$ 11.6	$ 57.5	$ 36.1
Intech Investment Management LLc
Long-term incentive compensation expense
Long-term incentive awards granted			2.0
Restricted Stock Awards
Long-term incentive compensation expense
Long-term incentive awards granted			$ 52.3
Number of price-vesting units granted			2.9
Weighted average price per share (in dollars per share)			$ 17.80
Mutual Fund Share Awards
Long-term incentive compensation expense
Long-term incentive awards granted			$ 23.2
Deferred Compensation Plans
Long-term incentive compensation expense
Total long-term incentive compensation	0.7	$ 0.9	1.0	$ 3.3
Profits and Phantom Interests | Intech Investment Management LLc
Long-term incentive compensation expense
Total long-term incentive compensation	$ 4.0		$ 11.3