Dispositions (Narrative) (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended	6 Months Ended	12 Months Ended
	Jul. 31, 2020	Sep. 30, 2020	Sep. 30, 2020	Mar. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Dec. 02, 2020	Dec. 01, 2020	Jun. 30, 2020	May 01, 2020	Apr. 30, 2020	Mar. 31, 2020
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net book value		$ 3,209,250	$ 3,209,250	$ 3,252,228	$ 3,244,166	$ 3,263,853			$ 3,239,354			$ 3,285,447
Gain on sale of business		$ 176	$ 28,270
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