Summary of Significant Accounting Policies (Narrative) (Details)		3 Months Ended		9 Months Ended
		Mar. 31, 2020 USD ($)	Mar. 31, 2019 USD ($)	Sep. 30, 2019 segment	Dec. 31, 2019 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Adoption of CECL	[1]	$ 0
Provision for credit losses		354,700,000	$ 14,500,000
Number of reportable segments | segment				1
Uninsured cash and cash equivalents		25,100,000			$ 186,100,000
CECL Impact on Net Income		121,600,000
CECL Impact on Net Income, Per Diluted Share		6.69
Restricted Cash and Cash Equivalents [Member]
Summary Of Significant Accounting Policies [Line Items]
Uninsured cash and cash equivalents		404,300,000			$ 326,700,000
New Consumer Loan Assignments [Member]
Summary Of Significant Accounting Policies [Line Items]
Provision for credit losses		157,900,000
Loans Receivable [Member]
Summary Of Significant Accounting Policies [Line Items]
Adoption of CECL	[1]	2,463,600,000
Provision for credit losses		$ 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.