LEASES (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013
Leases
Rent expense	$ 50,100	$ 45,800	$ 40,500
Net book value	112,350	116,289		$ 114,223	$ 119,677	$ 120,225	$ 113,144	$ 109,475	$ 106,249
Future minimum rental payments, by year and in the aggregate, under operating leases
2015	38,592
2016	31,187
2017	24,726
2018	18,879
2019	13,209
Thereafter	25,253
Total	151,846
Future minimum rental payments, by year and in the aggregate, under Capital Lease Obligations
2015	436
2016	404
2017	299
2018	73
Total	1,212
Office equipment under capital leases
Leases
Net book value	$ 1,100	$ 600