EMPLOYEE STOCK BENEFIT PLANS (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Stock-based compensation expense
Total pre-tax stock-based compensation expense	$ 9.4	$ 7.8
Net tax benefit related to stock-based compensation expense	(3.1)	(2.7)
Stock options
Stock-based compensation expense
Total pre-tax stock-based compensation expense	2.5	2.1
Performance share awards
Stock-based compensation expense
Total pre-tax stock-based compensation expense	1.4	2.3
Restricted stock units
Stock-based compensation expense
Total pre-tax stock-based compensation expense	$ 5.5	$ 3.4