Basis of Presentation and Summary of Significant Accounting Policies (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2018
Reclassification [Line Items]
Cost of revenue	$ 82.2	$ 69.0	$ 237.1	$ 182.6
Advertising expense	10.0	3.4	$ 15.6	8.6
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounting Standards Update [Extensible List]			us-gaap:AccountingStandardsUpdate201613Member		us-gaap:AccountingStandardsUpdate201613Member
Increase of accumulated deficit	(595.0)	(150.6)	$ (595.0)	(150.6)	$ (75.9)	$ (563.3)	$ (249.8)	$ (212.1)
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	4.6		3.8
Provision for expected credit losses	0.5		3.1	2.6
Write-offs charged against allowance	(1.6)		(4.7)
Recoveries of amounts previously written-off	0.1		0.3
Ending balance	3.6		3.6		3.8
Accounts and unbilled receivables
Reclassification [Line Items]
Reclassification of prior period amounts				0.9
Prepaid expenses and other assets
Reclassification [Line Items]
Reclassification of prior period amounts				0.9
Selling, general and administrative expenses
Reclassification [Line Items]
Reclassification of prior period amounts		0.6		1.9
Research and development expenses
Reclassification [Line Items]
Reclassification of prior period amounts		0.6		1.9
Cumulative Effect, Period of Adoption, Adjusted Balance
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	4.6		4.9
Ending balance					4.9
Cumulative Effect, Period of Adoption, Adjustment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Increase of accumulated deficit					1.1
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	0.0		1.1
Ending balance					1.1
Shipping and Handling
Reclassification [Line Items]
Cost of revenue	3.2	2.2	7.0	7.1
Accumulated Deficit
Accounts, Notes, Loans and Financing Receivable [Line Items]
Increase of accumulated deficit	$ 649.2	$ 677.0	$ 649.2	$ 677.0	672.0	$ 660.8	$ 677.8	$ 683.6
Accumulated Deficit | Cumulative Effect, Period of Adoption, Adjustment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Increase of accumulated deficit					$ 1.1