SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details 7) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Earnings per share:
Net income as reported and available to common stockholders									$ 56,738	$ 47,254	$ 48,828
Weighted average common shares outstanding, basic									47,791,000	46,384,000	41,892,000
Dilutive common stock options (treasury method)									38,000	33,000
Shares used for dilutive calculation									47,829,000	46,417,000	41,892,000
Earnings per share-basic									$ 1.19	$ 1.02	$ 1.17
Earnings per share-diluted	$ 0.24	$ 0.70	$ 0.36	$ (0.11)	$ 0.12	$ 0.61	$ 0.28	$ (0.03)	$ 1.19	$ 1.02	$ 1.17
Stock Appreciation Rights (SARs)
Stock-based awards included in earnings per share
Stock Appreciation Rights (SAR) outstanding	186,356				283,856				186,356	283,856	333,856