SEGMENT REPORTING - Financial Information of Company's Segments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Segment Reporting Information, Profit (Loss) [Abstract]
Total Revenue	$ 387,314	$ 289,494	$ 1,074,537	$ 820,772
Income from operations	48,377	32,839	132,870	92,837
Product sales | Recognized at a point in time
Segment Reporting Information, Profit (Loss) [Abstract]
Total Revenue	300,889	235,265	834,475	673,795
Inventory services | Recognized over time
Segment Reporting Information, Profit (Loss) [Abstract]
Total Revenue	5,893	4,302	17,010	12,761
Staffing services | Recognized over time
Segment Reporting Information, Profit (Loss) [Abstract]
Total Revenue	21,488	13,487	53,162	37,805
Pump production and delivery | Recognized over time
Segment Reporting Information, Profit (Loss) [Abstract]
Total Revenue	59,044	36,440	169,890	96,411
SC
Segment Reporting Information, Profit (Loss) [Abstract]
Total Revenue	260,083	212,539	729,977	608,542
Income from operations	35,718	29,381	95,437	77,819
SC | Product sales | Recognized at a point in time
Segment Reporting Information, Profit (Loss) [Abstract]
Total Revenue	238,595	199,052	676,815	570,737
SC | Inventory services | Recognized over time
Segment Reporting Information, Profit (Loss) [Abstract]
Total Revenue	0	0	0	0
SC | Staffing services | Recognized over time
Segment Reporting Information, Profit (Loss) [Abstract]
Total Revenue	21,488	13,487	53,162	37,805
SC | Pump production and delivery | Recognized over time
Segment Reporting Information, Profit (Loss) [Abstract]
Total Revenue	0	0	0	0
IPS
Segment Reporting Information, Profit (Loss) [Abstract]
Total Revenue	59,044	36,440	169,890	96,411
Income from operations	7,327	277	23,122	6,027
IPS | Product sales | Recognized at a point in time
Segment Reporting Information, Profit (Loss) [Abstract]
Total Revenue	0	0	0	0
IPS | Inventory services | Recognized over time
Segment Reporting Information, Profit (Loss) [Abstract]
Total Revenue	0	0	0	0
IPS | Staffing services | Recognized over time
Segment Reporting Information, Profit (Loss) [Abstract]
Total Revenue	0	0	0	0
IPS | Pump production and delivery | Recognized over time
Segment Reporting Information, Profit (Loss) [Abstract]
Total Revenue	59,044	36,440	169,890	96,411
SCS
Segment Reporting Information, Profit (Loss) [Abstract]
Total Revenue	68,187	40,515	174,670	115,819
Income from operations	5,332	3,181	14,311	8,991
SCS | Product sales | Recognized at a point in time
Segment Reporting Information, Profit (Loss) [Abstract]
Total Revenue	62,294	36,213	157,660	103,058
SCS | Inventory services | Recognized over time
Segment Reporting Information, Profit (Loss) [Abstract]
Total Revenue	5,893	4,302	17,010	12,761
SCS | Staffing services | Recognized over time
Segment Reporting Information, Profit (Loss) [Abstract]
Total Revenue	0	0	0	0
SCS | Pump production and delivery | Recognized over time
Segment Reporting Information, Profit (Loss) [Abstract]
Total Revenue	$ 0	$ 0	$ 0	$ 0