STOCK-BASED COMPENSATION (Details) (USD $) In Millions, except Share data, unless otherwise specified	9 Months Ended
	Sep. 30, 2014 item
Performance Shares
Stock-based compensation
Awards issued (in shares)	203,295
Estimated fair value of performance shares awarded	$ 10.5
Period over which average return on average equity is calculated	3 years
Minimum percentage of Company's ROE to earn awards under performance awards	10.50%
Number of awards earned when ROE is below 10.5%	0
Minimum percentage of Company's ROE to earn maximum awards under performance awards	12.00%
Restricted Stock Units
Stock-based compensation
Awards issued (in shares)	98,700
Estimated fair value of performance shares awarded	$ 5.1
Vesting percentage	50.00%
Restricted Stock Units | Vesting after three years from grant date
Stock-based compensation
Vesting period	3 years
Restricted Stock Units | Vesting after four years from grant date
Stock-based compensation
Vesting period	4 years
Stock Appreciation Rights
Stock-based compensation
Awards issued (in shares)	0
Vesting period	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)	$ 23.08
SARs exercised / forfeited (in dollars per share)	$ 21.94
Balance at the end of the period (in dollars per share)	$ 30.27
No. of SARs
Balance at the beginning of the period (in shares)	1,305,101
SARs exercised / forfeited (in shares)	(1,127,156)
Balance at the end of the period (in shares)	177,945
Stock Appreciation Rights | Minimum
Stock-based compensation
Number of annual installments to exercise stock appreciation rights	3
Stock Appreciation Rights | Maximum
Stock-based compensation
Number of annual installments to exercise stock appreciation rights	4