Dispositions (Narrative) (Details) - USD ($) $ in Thousands		1 Months Ended	3 Months Ended	6 Months Ended
	May 01, 2020	Jul. 31, 2020	Sep. 30, 2020	Sep. 30, 2020	Jun. 30, 2020	Apr. 30, 2020	Mar. 31, 2020	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			$ 3,209,250	$ 3,209,250	$ 3,239,354		$ 3,285,447	$ 1,886,107	$ 1,131,424	$ 1,132,487
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						$ 23,093
Net accounts receivable						16,575
Goodwill						21,705
Deferred revenue						$ 17,133
Gain on sale of business	24,608
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