EARNINGS PER SHARE (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Earnings per share
Net income	$ 11,464	$ 12,037	$ 10,358	$ 22,502
Average number of common shares issued	26,525	26,525	26,525	26,525
Less: average number of treasury shares	1,417	1,427	1,421	1,344
Less: average number of unvested stock award shares	393	319	397	318
Average number of basic common shares outstanding	24,715	24,779	24,707	24,863
Average number of diluted common shares outstanding	24,809	24,956	24,821	25,049
Earnings per share:
Basic (in dollars per share)	$ 0.46	$ 0.49	$ 0.42	$ 0.91
Diluted (in dollars per share)	$ 0.46	$ 0.48	$ 0.42	$ 0.90
Non-vested Stock Awards
Earnings per share
Plus: dilutive effect of share-based payment arrangements (in shares)	44	59	55	68
Stock Options
Earnings per share
Plus: dilutive effect of share-based payment arrangements (in shares)	50	118	59	118