Loan Sales and Servicing Activities - Summary of Cash Flows with Transferees (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash flows:
Sales proceeds	$ 154,450,942	$ 102,840,312	$ 61,214,102
Servicing fees received	840,104	678,142	$ 587,919
Period end information:
Unpaid principal balance of loans outstanding	254,524,015	199,655,361
30-89 days	6,129,597	6,041,366
90 days or more - Not in foreclosure	8,399,299	17,799,621
90 days or more - In foreclosure	715,016	581,683
90 days or more - Foreclosed	6,900	10,893
Bankruptcy	1,039,362	1,230,696
30-89 days delinquent under CARES Act	1,020,290	2,626,617
90 days or more delinquent not in foreclosure under CARES Act	2,550,703	12,181,174
Total delinquent loans in COVID-19 pandemic related forbearance	$ 3,570,993	$ 14,807,791