Loss Reserves - Delinquent Items (Details) - loan	Sep. 30, 2023	Jun. 30, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Dec. 31, 2021
Aging of the Primary Delinquent Inventory [Abstract]
3 months or less (in loans)	8,732		8,820	7,825
4 - 11 months (in loans)	8,220		8,217	7,619
12 months or more (in loans)	7,768		9,350	10,434
Total primary delinquent inventory (in loans)	24,720	23,823	26,387	25,878	26,855	33,290
3 months or less (as a percent)	35.00%		33.00%	30.00%
4 - 11 months (as a percent)	33.00%		31.00%	30.00%
12 months or more (as a percent)	32.00%		36.00%	40.00%
Total primary delinquent inventory (as a percent)	100.00%		100.00%	100.00%
Primary claims received inventory included in ending delinquent inventory (in loans)	284		267	244
Percent of 12 months or more delinquent inventory, delinquent for more than 36 months (as a percent)	39.00%		36.00%	33.00%