SEGMENT REPORTING, Reportable Segment Information (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2020 USD ($) Segment	Mar. 31, 2019 USD ($)	Mar. 31, 2018 USD ($)
SEGMENT REPORTING [Abstract]
Number of business segment | Segment									2
Reportable Segment Information [Abstract]
Net sales	$ 366,476	$ 428,991	$ 411,565	$ 381,372	$ 325,434	$ 345,664	$ 345,043	$ 356,532	$ 1,588,404	$ 1,372,673	$ 1,418,802
Cost of Sales [Abstract]
Total cost of sales	274,651	325,295	308,534	288,733	244,162	262,751	259,543	275,829	1,197,213	1,042,285	1,095,320
Gross profit	91,825	103,696	103,031	92,639	81,272	82,913	85,500	80,703	391,191	330,388	323,482
Selling, general, and administrative expenses	69,782	73,090	70,523	65,787	62,683	59,728	57,705	56,966	279,182	237,082	228,127
Depreciation and amortization	3,489	3,647	3,557	3,463	3,574	2,719	2,741	2,790	14,156	11,824	9,921
Interest and financing costs	676	694	576	628	545	443	484	476	2,574	1,948	1,195
Operating expenses	73,947	77,431	74,656	69,878	66,802	62,890	60,930	60,232	295,912	250,854	239,243
Operating income	17,878	26,265	28,375	22,761	14,470	20,023	24,570	20,471	95,279	79,534	84,239
Other income	(232)	997	(40)	(45)	5,556	721	322	97	680	6,696	(348)
Earnings before tax	17,646	27,262	28,335	22,716	20,026	20,744	24,892	20,568	95,959	86,230	83,891
Net Sales [Abstract]
Contracts with customers									1,519,096	1,311,982	1,369,957
Financing and other									69,308	60,691	48,845
Net sales	366,476	428,991	411,565	381,372	325,434	345,664	345,043	356,532	1,588,404	1,372,673	1,418,802
Selected Financial Data - Statement of Cash Flow [Abstract]
Depreciation and amortization									19,156	18,639	15,827
Purchases of property, equipment and operating lease equipment									7,009	11,629	7,590
Selected Financial Data - Balance Sheet [Abstract]
Total assets	909,113				786,198				909,113	786,198	755,471
Product [Member]
Reportable Segment Information [Abstract]
Net sales	317,621	378,569	363,497	335,601	280,460	310,443	309,475	322,817	1,395,288	1,223,195	1,289,307
Cost of Sales [Abstract]
Total cost of sales	244,638	293,209	278,863	260,063	216,662	241,856	238,134	255,812	1,076,773	952,464	1,023,590
Net Sales [Abstract]
Net sales	317,621	378,569	363,497	335,601	280,460	310,443	309,475	322,817	1,395,288	1,223,195	1,289,307
Service [Member]
Reportable Segment Information [Abstract]
Net sales	48,855	50,422	48,068	45,771	44,974	35,221	35,568	33,715	193,116	149,478	129,495
Cost of Sales [Abstract]
Total cost of sales	30,013	32,086	29,671	28,670	27,500	20,895	21,409	20,017	120,440	89,821	71,730
Net Sales [Abstract]
Net sales	48,855	$ 50,422	$ 48,068	$ 45,771	44,974	$ 35,221	$ 35,568	$ 33,715	193,116	149,478	129,495
Technology Segment [Member]
Reportable Segment Information [Abstract]
Net sales									1,530,138	1,329,520	1,372,765
Net Sales [Abstract]
Contracts with customers									1,514,507	1,308,405	1,356,225
Financing and other									15,631	21,115	16,540
Net sales									1,530,138	1,329,520	1,372,765
Operating Segments [Member] | Technology Segment [Member]
Reportable Segment Information [Abstract]
Net sales									1,530,138	1,329,520	1,372,765
Cost of Sales [Abstract]
Total cost of sales									1,189,550	1,034,858	1,085,478
Gross profit									340,588	294,662	287,287
Selling, general, and administrative expenses									264,123	226,112	214,980
Depreciation and amortization									14,016	11,812	9,918
Interest and financing costs									294	0	0
Operating expenses									278,433	237,924	224,898
Operating income									62,155	56,738	62,389
Net Sales [Abstract]
Contracts with customers									1,514,507	1,308,405	1,356,225
Financing and other									15,631	21,115	16,540
Net sales									1,530,138	1,329,520	1,372,765
Selected Financial Data - Statement of Cash Flow [Abstract]
Depreciation and amortization									14,516	12,661	10,461
Purchases of property, equipment and operating lease equipment									4,842	6,042	5,353
Selected Financial Data - Balance Sheet [Abstract]
Total assets	709,854				607,998				709,854	607,998	537,776
Operating Segments [Member] | Technology Segment [Member] | Product [Member]
Reportable Segment Information [Abstract]
Net sales									1,337,022	1,180,042	1,243,270
Cost of Sales [Abstract]
Total cost of sales									1,069,110	945,037	1,013,748
Net Sales [Abstract]
Net sales									1,337,022	1,180,042	1,243,270
Operating Segments [Member] | Technology Segment [Member] | Service [Member]
Reportable Segment Information [Abstract]
Net sales									193,116	149,478	129,495
Cost of Sales [Abstract]
Total cost of sales									120,440	89,821	71,730
Net Sales [Abstract]
Net sales									193,116	149,478	129,495
Operating Segments [Member] | Financing Segment [Member]
Reportable Segment Information [Abstract]
Net sales									58,266	43,153	46,037
Cost of Sales [Abstract]
Total cost of sales									7,663	7,427	9,842
Gross profit									50,603	35,726	36,195
Selling, general, and administrative expenses									15,059	10,970	13,147
Depreciation and amortization									140	12	3
Interest and financing costs									2,280	1,948	1,195
Operating expenses									17,479	12,930	14,345
Operating income									33,124	22,796	21,850
Net Sales [Abstract]
Contracts with customers									4,589	3,577	13,732
Financing and other									53,677	39,576	32,305
Net sales									58,266	43,153	46,037
Selected Financial Data - Statement of Cash Flow [Abstract]
Depreciation and amortization									4,640	5,978	5,366
Purchases of property, equipment and operating lease equipment									2,167	5,587	2,237
Selected Financial Data - Balance Sheet [Abstract]
Total assets	$ 199,259				$ 178,200				199,259	178,200	217,695
Operating Segments [Member] | Financing Segment [Member] | Product [Member]
Reportable Segment Information [Abstract]
Net sales									58,266	43,153	46,037
Cost of Sales [Abstract]
Total cost of sales									7,663	7,427	9,842
Net Sales [Abstract]
Net sales									58,266	43,153	46,037
Operating Segments [Member] | Financing Segment [Member] | Service [Member]
Reportable Segment Information [Abstract]
Net sales									0	0	0
Cost of Sales [Abstract]
Total cost of sales									0	0	0
Net Sales [Abstract]
Net sales									$ 0	$ 0	$ 0