Internal-Use Software Development Costs - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Capitalized software development costs	$ 6.9	$ 6.5	$ 20.8	$ 17.1
Amortization expense	4.7	$ 3.6	13.3	$ 10.0
Discontinued Operations, Disposed of by Sale \| MyCase
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Capitalized software divested	$ 3.9		$ 3.9

Disposal Group, Including Discontinued Operation, Capitalized Software

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Additions made to capitalized computer software costs during the period.

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Amount of expense for amortization of capitalized computer software costs.

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