GOODWILL AND OTHER INTANGIBLE ASSETS (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Goodwill [Roll Forward]
Beginning balance	$ 197,362
Purchase price adjustment	(151)
Translation adjustment	0
Amortization	0
Ending balance	197,211
Other Intangibles Assets [Roll Forward]
Balance at beginning of period	112,297
Purchase price adjustment	0
Translation adjustment	1,188
Amortization	(4,528)	$ (5,358)
Balance at end of period	108,957
Total Goodwill and Intangible Assets [Roll Forward]
Beginning Balance	309,659
Purchase price adjustment	(151)
Translation adjustment	1,188
Amortization	(4,528)	$ (5,358)
Ending Balance	306,168
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	198,287		$ 197,395
Accumulated amortization	(89,330)		(85,098)
Carrying amount, net	108,957		112,297
Service Centers [Member]
Goodwill [Roll Forward]
Beginning balance	164,244
Ending balance	164,093
Innovative Pumping Solutions [Member]
Goodwill [Roll Forward]
Beginning balance	15,980
Ending balance	15,980
Supply Chain Services [Member]
Goodwill [Roll Forward]
Beginning balance	17,138
Ending balance	17,138
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	196,482		195,580
Accumulated amortization	(87,915)		(83,741)
Carrying amount, net	108,567		111,839
Non-Compete Agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	1,805		1,815
Accumulated amortization	(1,415)		(1,357)
Carrying amount, net	$ 390		$ 458