Description of Business (Percentage of Consumer Loans Assigned Based on Volumes) (Details)		3 Months Ended
		Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019
Portfolio Program [Member]
Description Of Business [Line Items]
Percentage of new consumer loans unit volume		64.90%	67.40%	67.20%	66.70%	67.40%
Percentage of new consumer loans dollar volume	[1]	60.50%	64.00%	64.10%	63.70%	65.00%
Purchase Program [Member]
Description Of Business [Line Items]
Percentage of new consumer loans unit volume		35.10%	32.60%	32.80%	33.30%	32.60%
Percentage of new consumer loans dollar volume	[1]	39.50%	36.00%	35.90%	36.30%	35.00%

[1] Represents advances paid to Dealers on Consumer Loans assigned under our Portfolio Program and one-time payments made to Dealers to purchase Consumer Loans assigned under our Purchase Program. Payments of Dealer Holdback (as defined below) and accelerated Dealer Holdback are not included.