SEGMENT REPORTING, Reportable Segment Information (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) Segment	Sep. 30, 2019 USD ($)	Mar. 31, 2020 USD ($)
SEGMENT REPORTING [Abstract]
Number of business segments | Segment			2
Reportable Segment Information [Abstract]
Net sales	$ 433,081	$ 411,565	$ 788,112	$ 792,937
Cost of Sales [Abstract]
Cost of sales	334,119	308,534	590,593	597,267
Gross profit	98,962	103,031	197,519	195,670
Selling, general, and administrative	66,889	70,523	136,356	136,310
Depreciation and amortization	3,341	3,557	6,857	7,020
Interest and financing costs	247	576	824	1,204
Operating expenses	70,477	74,656	144,037	144,534
Operating income	28,485	28,375	53,482	51,136
Other income (expense)	184	(40)	282	(85)
Earnings before tax	28,669	28,335	53,764	51,051
Net Sales [Abstract]
Contracts with customers	413,385	395,996	748,332	760,466
Financing and other	19,696	15,569	39,780	32,471
Net sales	433,081	411,565	788,112	792,937
Selected Financial Data - Statement of Cash Flow [Abstract]
Depreciation and amortization	4,681	5,113	9,460	10,077
Purchases of property, equipment and operating lease equipment	990	3,370	3,267	4,888
Selected Financial Data - Balance Sheet [Abstract]
Total assets	1,038,711	914,266	1,038,711	914,266	$ 909,113
Product [Member]
Reportable Segment Information [Abstract]
Net sales	383,656	363,497	690,896	699,098
Cost of Sales [Abstract]
Cost of sales	302,963	278,863	529,597	538,926
Net Sales [Abstract]
Net sales	383,656	363,497	690,896	699,098
Service [Member]
Reportable Segment Information [Abstract]
Net sales	49,425	48,068	97,216	93,839
Cost of Sales [Abstract]
Cost of sales	31,156	29,671	60,996	58,341
Net Sales [Abstract]
Net sales	49,425	48,068	97,216	93,839
Technology Segment [Member]
Reportable Segment Information [Abstract]
Net sales	419,359	397,718	760,583	766,253
Net Sales [Abstract]
Contracts with customers	412,357	394,585	746,344	758,266
Financing and other	7,002	3,133	14,239	7,987
Net sales	419,359	397,718	760,583	766,253
Operating Segments [Member] | Technology Segment [Member]
Reportable Segment Information [Abstract]
Net sales	419,359	397,718	760,583	766,253
Cost of Sales [Abstract]
Cost of sales	332,162	306,146	586,545	592,870
Gross profit	87,197	91,572	174,038	173,383
Selling, general, and administrative	62,586	67,189	128,142	129,856
Depreciation and amortization	3,313	3,529	6,801	6,936
Interest and financing costs	1	0	266	0
Operating expenses	65,900	70,718	135,209	136,792
Operating income	21,297	20,854	38,829	36,591
Net Sales [Abstract]
Contracts with customers	412,357	394,585	746,344	758,266
Financing and other	7,002	3,133	14,239	7,987
Net sales	419,359	397,718	760,583	766,253
Selected Financial Data - Statement of Cash Flow [Abstract]
Depreciation and amortization	3,499	3,658	7,133	7,283
Purchases of property, equipment and operating lease equipment	990	1,426	3,101	2,675
Selected Financial Data - Balance Sheet [Abstract]
Total assets	812,633	690,648	812,633	690,648
Operating Segments [Member] | Technology Segment [Member] | Product [Member]
Reportable Segment Information [Abstract]
Net sales	369,934	349,650	663,367	672,414
Cost of Sales [Abstract]
Cost of sales	301,006	276,475	525,549	534,529
Net Sales [Abstract]
Net sales	369,934	349,650	663,367	672,414
Operating Segments [Member] | Technology Segment [Member] | Service [Member]
Reportable Segment Information [Abstract]
Net sales	49,425	48,068	97,216	93,839
Cost of Sales [Abstract]
Cost of sales	31,156	29,671	60,996	58,341
Net Sales [Abstract]
Net sales	49,425	48,068	97,216	93,839
Operating Segments [Member] | Financing Segment [Member]
Reportable Segment Information [Abstract]
Net sales	13,722	13,847	27,529	26,684
Cost of Sales [Abstract]
Cost of sales	1,957	2,388	4,048	4,397
Gross profit	11,765	11,459	23,481	22,287
Selling, general, and administrative	4,303	3,334	8,214	6,454
Depreciation and amortization	28	28	56	84
Interest and financing costs	246	576	558	1,204
Operating expenses	4,577	3,938	8,828	7,742
Operating income	7,188	7,521	14,653	14,545
Net Sales [Abstract]
Contracts with customers	1,028	1,411	1,988	2,200
Financing and other	12,694	12,436	25,541	24,484
Net sales	13,722	13,847	27,529	26,684
Selected Financial Data - Statement of Cash Flow [Abstract]
Depreciation and amortization	1,182	1,455	2,327	2,794
Purchases of property, equipment and operating lease equipment	0	1,944	166	2,213
Selected Financial Data - Balance Sheet [Abstract]
Total assets	226,078	223,618	226,078	223,618
Operating Segments [Member] | Financing Segment [Member] | Product [Member]
Reportable Segment Information [Abstract]
Net sales	13,722	13,847	27,529	26,684
Cost of Sales [Abstract]
Cost of sales	1,957	2,388	4,048	4,397
Net Sales [Abstract]
Net sales	13,722	13,847	27,529	26,684
Operating Segments [Member] | Financing Segment [Member] | Service [Member]
Reportable Segment Information [Abstract]
Net sales	0	0	0	0
Cost of Sales [Abstract]
Cost of sales	0	0	0	0
Net Sales [Abstract]
Net sales	$ 0	$ 0	$ 0	$ 0