Summary of Significant Accounting Policies $ in Millions		3 Months Ended		6 Months Ended		12 Months Ended
		Jun. 30, 2021 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2021 USD ($)	Jun. 30, 2020 USD ($)	Dec. 31, 2020 USD ($) segment
Summary Of Significant Accounting Policies [Line Items]
Number of reportable segments | segment						1
Uninsured cash and cash equivalents		$ 382.4		$ 382.4		$ 15.7
Adoption of CECL	[1]				$ 0.0
Provision for credit losses		(30.5)	$ 139.4	(9.2)	494.1
Restricted Cash and Cash Equivalents [Member]
Summary Of Significant Accounting Policies [Line Items]
Uninsured cash and cash equivalents		474.2		474.2		$ 376.9
New Consumer Loan Assignments [Member]
Summary Of Significant Accounting Policies [Line Items]
Provision for credit losses		91.6	154.2	223.4	312.1
Loans Receivable [Member]
Summary Of Significant Accounting Policies [Line Items]
Adoption of CECL	[1]				2,463.6
Provision for credit losses		$ 0.0	$ 0.0	$ 0.0	$ 0.0

[1] Represents the gross-up of Loans receivable and allowance for credit losses on January 1, 2020 upon the adoption of CECL for the present value of the difference between contractual future net cash flows and expected future net cash flows discounted at the effective interest rate.