GOODWILL AND OTHER INTANGIBLE ASSETS (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Goodwill [Roll Forward]
Beginning balance	$ 145,788
Acquired during the year	0
Adjustments to prior year estimates	1,559
Ending balance	147,347	145,788
Other Intangibles Assets [Roll Forward]
Balance at beginning of period	63,189
Acquired during the year	0
Adjustments to prior year estimates	(2,416)
Amortization	(2,642)	(2,234)
Balance at end of period	58,131
Total Goodwill and Intangible Assets [Roll Forward]
Beginning Balance	208,977
Acquired during the year	0
Adjustment to prior year estimates	(857)
Amortization	(2,642)	(2,234)
Ending Balance	205,478
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	92,472		94,888
Accumulated amortization	(34,341)		(31,699)
Carrying amount, net	58,131		63,189
Service Centers [Member]
Goodwill [Roll Forward]
Ending balance	114,228	112,669
Innovative Pumping Solutions [Member]
Goodwill [Roll Forward]
Ending balance	15,980	15,980
Supply Chain Services [Member]
Goodwill [Roll Forward]
Ending balance	17,139	17,139
Vendor Agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	2,496		2,496
Accumulated amortization	(1,112)		(1,081)
Carrying amount, net	1,384		1,415
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	88,435		90,851
Accumulated amortization	(32,553)		(30,010)
Carrying amount, net	55,882		60,841
Non-Compete Agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	1,541		1,541
Accumulated amortization	(676)		(608)
Carrying amount, net	865		933
Customer Lists [Member] | Intangible Assets Related to Jerzy Acquisition [Member]
Goodwill [Roll Forward]
Adjustments to prior year estimates	300
Customer Lists [Member] | Intangible Assets Related to HSE Acquisition [Member]
Goodwill [Roll Forward]
Adjustments to prior year estimates	$ 2,800