GOODWILL AND OTHER INTANGIBLE ASSETS (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Goodwill [Roll Forward]
Beginning balance	$ 101,764	$ 84,942
Acquired during the year	44,074	15,822
Adjustments to prior year estimates	(50)
Payment of earnout		1,000
Ending balance	145,788	101,764	84,942
Other Intangibles Assets [Roll Forward]
Balance at beginning of period	43,194	32,236
Acquired during the year	30,831	17,530
Adjustments to prior year estimates	50
Amortization	(10,886)	(6,572)	(5,824)
Balance at end of period	63,189	43,194	32,236
Total Goodwill and Intangible Assets [Roll Forward]
Beginning Balance	144,958	117,178
Acquired during the year	74,905	33,352
Adjustment to prior year estimates	0
Payment of earn out		1,000
Amortization	(10,886)	(6,572)	(5,824)
Ending Balance	208,977	144,958	117,178
Changes in the carrying amount of goodwill by segment [Abstract]
Goodwill	145,788	101,764	84,942
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	94,888	69,369
Accumulated amortization	(31,699)	(26,175)
Carrying amount, net	63,189	43,194
The estimated future annual amortization of intangible assets for each of the next five years and thereafter [Abstract]
2013	11,747
2014	11,473
2015	10,039
2016	7,735
2017	7,686
Thereafter	14,509
Vendor Agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	2,496	2,496
Accumulated amortization	(1,081)	(956)
Carrying amount, net	1,415	1,540
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	90,851	64,262
Accumulated amortization	(30,010)	(23,508)
Carrying amount, net	60,841	40,754
Non-Compete Agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	1,541	2,611
Accumulated amortization	(608)	(1,711)
Carrying amount, net	933	900
Service Centers [Member]
Goodwill [Roll Forward]
Ending balance	121,901	77,877
Changes in the carrying amount of goodwill by segment [Abstract]
Goodwill	121,901	77,877
Innovative Pumping Solutions [Member]
Goodwill [Roll Forward]
Ending balance	15,980	15,980
Changes in the carrying amount of goodwill by segment [Abstract]
Goodwill	15,980	15,980
Supply Chain Services [Member]
Goodwill [Roll Forward]
Ending balance	7,907	7,907
Changes in the carrying amount of goodwill by segment [Abstract]
Goodwill	$ 7,907	$ 7,907