Dispositions (Narrative) (Details) - USD ($) $ in Thousands			1 Months Ended	3 Months Ended	9 Months Ended
	Dec. 02, 2020	May 01, 2020	Jul. 31, 2020	Dec. 31, 2020	Dec. 31, 2020	Dec. 01, 2020	Sep. 30, 2020	Jun. 30, 2020	Apr. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net book value				$ 3,233,738	$ 3,233,738		$ 3,209,250	$ 3,239,354		$ 3,285,447	$ 1,950,131	$ 1,886,107	$ 1,131,424	$ 1,132,487
Gain on sale of business				$ 32,217	$ 60,487
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									$ 22,619
Net accounts receivable									16,325
Goodwill									21,705
Deferred revenue									$ 17,133
Gain on sale of business		24,170
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						$ 31,599
Net accounts receivable						14,999
Goodwill						26,944
Deferred revenue						$ 15,230
Gain on sale of business	$ 32,655