Dispositions (Narrative) (Details) - USD ($) $ in Thousands			1 Months Ended	12 Months Ended
	Dec. 02, 2020	May 01, 2020	Jul. 31, 2020	Mar. 31, 2021	Dec. 01, 2020	Apr. 30, 2020	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net book value				$ 3,252,228			$ 3,285,447	$ 1,132,487	$ 1,176,572
Gain on sale of business				$ 59,143
Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] | Connected Analytics [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration		$ 55,000
Net book value						$ 23,428
Net accounts receivable						16,636
Goodwill						21,705
Deferred revenue						$ 17,083
Gain on sale of business		24,337
Payment received on notes receivable			$ 25,000
Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] | Connected Analytics [Member] | Notes Receivable [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Other noncurrent assets		$ 25,000
Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] | Capacity Management [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration	$ 67,500
Net book value					$ 31,690
Net accounts receivable					14,991
Goodwill					26,944
Deferred revenue					$ 15,230
Gain on sale of business	$ 31,690