SEGMENT REPORTING (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
Segment Reporting Information [Line Items]
Sales	$ 261,894	$ 197,675	$ 514,181	$ 380,762
Operating income for reportable segments	33,332	22,561	62,951	42,114
Adjustment for [Abstract]
Amortization of intangibles	2,556	1,604	4,790	3,210
Corporate and other expense, net	9,929	7,326	17,409	13,731
Operating income	20,847	13,631	40,752	25,173
Interest expense, net	762	1,023	1,591	2,045
Other expense (income), net	3	(15)	(12)	(36)
Income before income taxes	20,082	12,623	39,173	23,164
Service Centers [Member]
Segment Reporting Information [Line Items]
Sales	184,106	139,503	359,178	271,054
Operating income for reportable segments	22,491	17,340	41,045	32,121
Innovative Pumping Solutions [Member]
Segment Reporting Information [Line Items]
Sales	35,177	21,814	74,612	38,499
Operating income for reportable segments	6,939	3,085	15,187	5,943
Supply Chain Services [Member]
Segment Reporting Information [Line Items]
Sales	42,611	36,358	80,391	71,209
Operating income for reportable segments	$ 3,902	$ 2,136	$ 6,719	$ 4,050