STOCK-BASED COMPENSATION (Details) (USD $) In Millions, except Share data, unless otherwise specified	6 Months Ended
	Jun. 30, 2013 item
Performance awards
Stock-based compensation
Awards issued	298,500
Estimated fair value of performance shares awarded	$ 9.3
Period over which average return on average equity is calculated	3 years
Minimum percentage of Company's ROE to earn awards under performance awards	10.00%
Number of awards earned when ROE is below 10.0%	0
Minimum percentage of Company's ROE to earn maximum awards under performance awards	11.50%
SARs
Stock-based compensation
Exercisable period of grants from grant date	5 years
Beginning of annual installments from date of grant	1 year
Expiration period from date of grant	10 years
Weighted-Average Base Price per share
Balance at the beginning of the period (in dollars per share)	$ 22.15
SARs exercised / forfeited (in dollars per share)	$ 25.68
Balance at the end of the period (in dollars per share)	$ 21.84
No. of Awards
Balance at the beginning of the period (in shares)	1,641,167
Awards exercised / forfeited	(132,849)
Balance at the end of the period (in shares)	1,508,318
SARs | Minimum
Stock-based compensation
Number of annual installments to exercise stock appreciation rights	3
SARs | Maximum
Stock-based compensation
Number of annual installments to exercise stock appreciation rights	4
Restricted stock units
Stock-based compensation
Awards issued	141,000
Estimated fair value of performance shares awarded	$ 4.4
Vesting percentage	50.00%