Summary of Significant Accounting Policies - Capitalized Software and Hardware - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment
Amortization expense	$ 3.7	$ 3.1	$ 3.2
Prepaid Expenses and Other Current Assets
Property, Plant and Equipment
Capitalized internal use software and hardware	$ 6.0	$ 5.7
Minimum
Property, Plant and Equipment
Amortization period	1 year
Maximum
Property, Plant and Equipment
Amortization period	5 years