SHARE-BASED COMPENSATION (Details 2) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based compensation
Vesting period	4 years
Method and assumptions on valuation of stock options
Expected dividend yield (as a percent)	0.00%	0.00%	0.00%
Additional disclosures
Proceeds from exercise of stock options	$ 17.2	$ 10.0	$ 23.0
Stock options
Share-based compensation
Number of days average trading price as base for minimum exercise price of stock option granted	5 days
Percentage of stock options that will vest on each of the first, second, third and fourth anniversaries from the date of grant	25.00%
Method and assumptions on valuation of stock options
Expected stock option life (years)	5 years 9 months 18 days	4 years	4 years
Expected volatility (as a percent)	43.00%	40.10%	44.90%
Risk-free interest rate (as a percent)	1.80%	1.00%	0.50%
Stock option activity
Options outstanding at the beginning of the period (in shares)	8.6
Granted (in shares)	0.3
Exercised (in shares)	(0.8)
Expired or forfeited (in shares)	(0.4)
Options outstanding at the end of the period (in shares)	7.7	8.6
Options vested and exercisable at the end of the period (in shares)	5.7
Weighted-average exercise price
Options outstanding at the beginning of the period (in dollars per share)	$ 30.19
Granted (in dollars per share)	$ 117.82
Exercised (in dollars per share)	$ 21.78
Expired or forfeited (in dollars per share)	$ 74.88
Options outstanding at the end of the period (in dollars per share)	$ 31.44	$ 30.19
Options vested and exercisable at the end of the period (in dollars per share)	$ 17.75
Weighted-Average Remaining Contractual Term
Options outstanding at the end of the period	4 years 9 months 18 days
Options vested and exercisable at the end of the period	4 years
Aggregate Intrinsic Value
Options outstanding at the end of the period	852.6
Options vested and exercisable at the end of the period	720.6
Additional disclosures
Weighted-average grant date fair value of stock options (in dollars per share)	$ 62.15	$ 30.47	$ 19.57
Intrinsic value of stock options exercised in the period	87.4	30.4	25.1
Proceeds from exercise of stock options	17.2	10.0	23.0
Remaining unrecognized compensation expense related to non-vested awards	42.2
Weighted-average remaining requisite service period over which unrecognized compensation cost is expected to be amortized	3 years 4 months 15 days
Total fair value of stock options vested during the period	$ 36.3	$ 26.0	$ 36.1