ACQUISITIONS: Purchase price allocation related to assets acquired and liabilities assumed (Details) € in Thousands, $ in Thousands							12 Months Ended
	Feb. 17, 2021 USD ($)	Feb. 17, 2021 EUR (€)	Jul. 16, 2020 USD ($)	Jul. 02, 2019 USD ($)	Jul. 02, 2019 EUR (€)	Apr. 02, 2019 USD ($)	Mar. 31, 2021 USD ($)	Mar. 31, 2020 USD ($)	Mar. 31, 2019 USD ($)
Business Acquisition [Line Items]
Goodwill							$ 357,446	$ 297,796	$ 204,656
Net cash paid							$ 76,012	105,365	$ 0
DataFleets, Ltd
Business Acquisition [Line Items]
Cash	$ 2,099
Goodwill	56,436
Intangible assets	11,400
Other current and noncurrent assets	1,119
Total assets acquired	71,054
Deferred income taxes	(1,716)
Accounts payable and accrued expenses	(75)
Net assets acquired	69,263
Cash acquired	(2,099)
Net purchase price allocated	67,164
Restricted cash held in escrow	(8,900)
Net cash paid	$ 58,264	€ 58,264
Acuity Data
Business Acquisition [Line Items]
Cash			$ 184
Goodwill			2,011
Intangible assets			1,100
Trade accounts receivable			156
Other current and noncurrent assets			43
Total assets acquired			3,494
Deferred income taxes			(288)
Accounts payable and accrued expenses			(89)
Net assets acquired			3,117
Cash acquired			(184)
Net cash paid			$ 2,933
Data Plus Math Corporation
Business Acquisition [Line Items]
Cash				$ 438
Goodwill				90,619
Intangible assets				34,000
Trade accounts receivable				957
Other current and noncurrent assets				1,186
Total assets acquired				127,200
Deferred income taxes				(6,034)
Accounts payable and accrued expenses				(2,727)
Net assets acquired				118,439
Cash acquired				(438)
Net purchase price allocated				118,001
Restricted cash held in escrow				(14,815)
Fair value of replacement stock options considered a component of purchase price				(2,300)				$ (2,300)
Net cash paid				$ 100,886	€ 100,886
Faktor B. V.
Business Acquisition [Line Items]
Cash						$ 35
Goodwill						3,110
Intangible assets						1,700
Trade accounts receivable						63
Other current and noncurrent assets						126
Total assets acquired						5,034
Deferred income taxes						(194)
Accounts payable and accrued expenses						(326)
Net assets acquired						4,514
Cash acquired						(35)
Net cash paid						$ 4,479