Summary of Significant Accounting Policies - Deferred Sales Commissions (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Deferred Sales Commissions
Total net capitalized costs	$ 30.4	$ 9.4
Amortization of capitalized costs of obtaining a contract	$ 4.5	$ 1.4
Incremental commission costs of obtaining new contracts
Deferred Sales Commissions
Amortization period for deferred incremental commission costs of obtaining new contracts	5 years