Significant Accounting Policies - Revenue Disaggregation and Customer-Related Liabilities (Details) $ in Millions	3 Months Ended
	Mar. 31, 2021 USD ($) type agreement	Dec. 31, 2020 USD ($)
Disaggregation of Revenue [Line Items]
Contract With Customer, Liability, Number Of Liability Types | type	3
Online sports betting and iGaming market access
Disaggregation of Revenue [Line Items]
Customer-related liabilities	$ 54.8	$ 52.7
Number of operator agreements containing ordinary shares and warrants | agreement	2
Loyalty Credit Obligation
Disaggregation of Revenue [Line Items]
Customer-related liabilities	$ 39.0	35.8
Customer-related liabilities, term	6 months
Advance Payments on Goods and Services Yet to Be Provided and Unpaid Wagers
Disaggregation of Revenue [Line Items]
Customer-related liabilities	$ 63.6	47.1
Customer-related liabilities, long-term	$ 0.5	$ 0.5