ACQUISITIONS: Purchase price allocation related to assets acquired and liabilities assumed (Details) - USD ($) $ in Thousands		6 Months Ended
	Jul. 16, 2020	Sep. 30, 2020	Sep. 30, 2019	Mar. 31, 2020
Business Acquisition [Line Items]
Goodwill		$ 300,741		$ 297,796
Net cash paid		$ 2,933	$ 105,365
Acuity Data
Business Acquisition [Line Items]
Cash	$ 184
Trade accounts receivable	156
Goodwill	2,011
Intangible assets	1,100
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