Loan Sales and Servicing Activities - Geographical Distribution of Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Loan Sales and Servicing Activities
Total loans serviced	$ 401,896,800	$ 368,684,232
California
Loan Sales and Servicing Activities
Total loans serviced	58,062,643	57,311,867
Florida
Loan Sales and Servicing Activities
Total loans serviced	33,545,822	28,940,696
Texas
Loan Sales and Servicing Activities
Total loans serviced	31,893,436	27,909,821
Virginia
Loan Sales and Servicing Activities
Total loans serviced	24,378,162	22,115,619
Maryland
Loan Sales and Servicing Activities
Total loans serviced	18,700,592	16,829,320
All other states
Loan Sales and Servicing Activities
Total loans serviced	$ 235,316,145	$ 215,576,909