LEASES (Details) (USD $)	12 Months Ended
	Dec. 31, 2011 Y	Dec. 31, 2010	Dec. 31, 2009
LEASES
Operating leases, expiration period (in years)	90
Total rental expense under operating leases	$ 17,800,000	$ 13,900,000	$ 10,600,000
Minimum future obligations on operating leases
2012	11,495,000
2013	9,137,000
2014	7,094,000
2015	5,745,000
2016	4,642,000
Thereafter	33,379,000
Total minimum obligations	$ 71,492,000