SEGMENT REPORTING - Financial Information of Company's Segments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Total revenue	$ 1,678,600	$ 1,480,832	$ 1,113,921
Operating income for reportable segments, excluding adjustments	229,661	176,741	122,964
Identifiable assets at year end	986,669	981,380	821,242
Capital expenditures	10,623	3,968	3,598
Depreciation	6,458	7,731	8,134
Amortization of intangibles	18,231	18,915	17,197
Service Centers
Segment Reporting Information [Line Items]
Total revenue	1,145,082	1,009,356	816,496
Operating income for reportable segments, excluding adjustments	163,877	127,174	98,931
Identifiable assets at year end	697,438	746,548	642,184
Capital expenditures	8,837	1,419	999
Depreciation	2,705	3,038	3,475
Amortization of intangibles	12,266	12,294	11,107
Innovative Pumping Solutions
Segment Reporting Information [Line Items]
Total revenue	273,150	231,102	139,591
Operating income for reportable segments, excluding adjustments	44,260	30,037	12,070
Identifiable assets at year end	226,621	144,352	134,374
Capital expenditures	1,786	2,506	2,574
Depreciation	3,726	4,549	4,270
Amortization of intangibles	5,965	6,621	6,090
Supply Chain Services
Segment Reporting Information [Line Items]
Total revenue	260,368	240,374	157,834
Operating income for reportable segments, excluding adjustments	21,524	19,530	11,963
Identifiable assets at year end	62,610	90,480	44,684
Capital expenditures	0	43	25
Depreciation	27	144	389
Amortization of intangibles	$ 0	$ 0	$ 0