GOODWILL AND OTHER INTANGIBLE ASSETS (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011
Total Goodwill and Intangible Assets [Roll Forward]
Balance at beginning of period			$ 144,958
Acquired during the year			35,442
Adjustment to prior year estimates			0
Amortization	(2,556)	(1,604)	(4,790)	(3,210)
Balance as of end of period	175,610		175,610
Goodwill [Roll Forward]
Balance at beginning of period			101,764
Acquired during the year			18,130
Adjustments to prior year estimates			(50)
Balance at end of period	119,844		119,844
Other Intangibles [Roll Forward]
Balance at beginning of period			43,194
Acquired during the year			17,312
Adjustments to prior year estimates			50
Amortization	(2,556)	(1,604)	(4,790)	(3,210)
Balance at end of period	55,766		55,766
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	86,731		86,731		69,369
Accumulated amortization	(30,965)		(30,965)		(26,175)
Vendor Agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	2,496		2,496		2,496
Accumulated amortization	(1,018)		(1,018)		(956)
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	81,022		81,022		64,262
Accumulated amortization	(28,078)		(28,078)		(23,508)
Non-Compete Agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	3,213		3,213		2,611
Accumulated amortization	$ (1,869)		$ (1,869)		$ (1,711)