Loans and Allowance for Loan Losses (Narrative) (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($) contract	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($) contract	Mar. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Mar. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest income on non-accrual loans outstanding	$ 6,600,000	$ 2,000,000	$ 9,900,000	$ 5,400,000
Interest income, cash basis method	7,800,000	410,000	9,400,000	964,000
Total loans	44,353,537,000		44,353,537,000			$ 43,716,353,000
Payments to acquire finance receivables	10,600,000		10,623,000	361,567,000
Financing receivable, allowance for credit loss, period increase (decrease) from increase in size of loan profile	711,000	3,700,000		7,500,000
Financing receivable, purchase		180,200,000		361,600,000
Allowance for loan losses	471,238,000	407,837,000	471,238,000	407,837,000	$ 457,010,000	443,424,000	$ 414,956,000	$ 427,597,000
Reserve for unfunded commitments	55,700,000		55,700,000			57,500,000
Increase in allowance for credit loss			26,100,000
All financing receivable, allowance for credit loss	$ 527,000,000		$ 527,000,000			$ 500,900,000
ACL to loans ratio (as percent)	1.19%		1.19%
Increase (decrease) in ACL to loans ratio			0.0004
Allowance for credit loss, reasonable and supportable forecast period (in year)			2 years
Allowance for credit loss, straight-line basis historical period (in year)			1 year
Allowance for credit loss, measurement input, estimated peak weighted average unemployment rate	5.70%		5.70%			5.10%
FDMs, subsequent default	$ 0	$ 430,000	$ 0	$ 430,000
Number of contracts | contract		3		3
Commitments to land additional funds to TDRs		$ 0		$ 0		$ 0
Total consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Charge-off of previously established reserves for credit losses associated with the transfer to held for sale	1,300,000		7,900,000
Reclassification to held-for-sale		3,800,000		427,900,000
Allowance for loan losses	141,525,000	$ 143,611,000	$ 141,525,000	$ 143,611,000	$ 137,930,000	138,299,000	$ 141,538,000	$ 141,473,000
Substandard
Accounts, Notes, Loans and Financing Receivable [Line Items]
Retail loan substandard period (in days)			90 days
Loss
Accounts, Notes, Loans and Financing Receivable [Line Items]
Retail loan charge off (in days)			120 days
Asset Pledged as Collateral
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 23,470,000,000		$ 23,470,000,000			$ 16,090,000,000.00