Loss Reserves - Delinquent Items (Details) - loan	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021	Dec. 31, 2020
Aging of the Primary Delinquent Inventory [Abstract]
3 months or less (in loans)	7,382	7,586	9,194
4 - 11 months (in loans)	8,131	7,990	29,832
12 months or more (in loans)	14,949	17,714	13,749
Total primary delinquent inventory (in loans)	30,462	33,290	52,775	57,710
3 months or less (as a percent)	24.00%	23.00%	17.00%
4 - 11 months (as a percent)	27.00%	24.00%	57.00%
12 months or more (as a percent)	49.00%	53.00%	26.00%
Total primary delinquent inventory (as a percent)	100.00%	100.00%	100.00%
Primary claims received inventory included in ending delinquent inventory (in loans)	217	211	151
Percent of 12 months or more delinquent inventory, delinquent for more than 36 months (as a percent)	23.00%	20.00%	26.00%