SHARE-BASED COMPENSATION - Additional Information (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended				1 Months Ended		6 Months Ended	1 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014 Restricted Stock	Jun. 30, 2014 Phantom Stock [Member]	Feb. 28, 2014 Performance Based Units	Jan. 31, 2014 Performance Based Units	Jun. 30, 2014 Performance Based Units	May 31, 2014 Outside directors	May 31, 2013 Outside directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense recognized	$ 2.4	$ 2.2	$ 7.1	$ 8.1						$ 1.6	$ 1.8
Income tax benefit recognized related to share-based awards	0.7	0.9	2.3	3.1
Compensation expense expected to be recognized					13.6				3.3
Compensation expense expected to be recognized, weighted average remaining vesting period					1 year 5 months				1 year 1 month
Shares outstanding (shares)						0
Shares of common stock issued										197,865
Performance units issued							100,000	500,000
Award requisite service period			2 years
Fair value of outstanding performance units issued	$ 6.0		$ 6.0