Loss Reserves - Delinquent Items (Details) - loan	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022	Dec. 31, 2021
Aging of the Primary Delinquent Inventory [Abstract]
3 months or less (in loans)	7,573	8,820	7,382
4 - 11 months (in loans)	8,563	8,217	8,131
12 months or more (in loans)	8,621	9,350	14,949
Total primary delinquent inventory (in loans)	24,757	26,387	30,462	33,290
3 months or less (as a percent)	31.00%	33.00%	24.00%
4 - 11 months (as a percent)	34.00%	31.00%	27.00%
12 months or more (as a percent)	35.00%	36.00%	49.00%
Total primary delinquent inventory (as a percent)	100.00%	100.00%	100.00%
Primary claims received inventory included in ending delinquent inventory (in loans)	296	267	217
Percent of 12 months or more delinquent inventory, delinquent for more than 36 months (as a percent)	38.00%	36.00%	23.00%