EARNINGS PER SHARE (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended			6 Months Ended
	Jun. 30, 2013	Mar. 31, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Basic earnings per share:
Net earnings from continuing operations	$ 4,396	$ 13,494	$ 15,557	$ 17,890	$ 20,821
Less: earnings allocated to unvested restricted stock	(212)	(326)	(538)	(351)	(602)
Net earnings from continuing operations allocated to common shares	4,184	13,168	15,019	17,539	20,219
Net earnings from discontinued operations	(47)			(47)
Net earnings allocated to common shares	4,137	13,168	15,019	17,492	20,219
Weighted-average basic shares and unvested restricted stock outstanding	40,338,300	37,391,100	37,359,200	38,872,800	37,321,600
Less: weighted-average unvested restricted stock outstanding (in shares)	(1,596,700)	(1,594,100)	(1,669,200)	(1,595,400)	(1,661,600)
Weighted-average basic shares outstanding	38,741,600	35,797,000	35,690,000	37,277,400	35,660,000
Net earnings from continuing operations (in dollars per share)	$ 0.11	$ 0.37	$ 0.42	$ 0.47	$ 0.57
Net earnings from discontinuing operations (in dollars per share)	$ 0.00	$ 0.00	$ 0.00	$ 0.00	$ 0.00
Net earnings (in dollars per share)	$ 0.11	$ 0.37	$ 0.42	$ 0.47	$ 0.57
Diluted earnings per share:
Net earnings from continuing operations allocated to common shares	4,184	13,168	15,019	17,539	20,219
Net earnings from discontinued operations	(47)			(47)
Net earnings allocated to common shares	$ 4,137	$ 13,168	$ 15,019	$ 17,492	$ 20,219
Weighted-average basic shares outstanding	38,741,600	35,797,000	35,690,000	37,277,400	35,660,000
Net earnings from continuing operations (in dollars per share)	$ 0.11	$ 0.37	$ 0.42	$ 0.47	$ 0.57
Net earnings from discontinuing operations (in dollars per share)	$ 0.00	$ 0.00	$ 0.00	$ 0.00	$ 0.00
Net earnings (in dollars per share)	$ 0.11	$ 0.37	$ 0.42	$ 0.47	$ 0.57