Loan Sales and Servicing Activities - Geographical Distribution of Loans (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Loan Sales and Servicing Activities
Total loans serviced	$ 384,226,626	$ 368,684,232
California
Loan Sales and Servicing Activities
Total loans serviced	58,058,528	57,311,867
Florida
Loan Sales and Servicing Activities
Total loans serviced	31,714,639	28,940,696
Texas
Loan Sales and Servicing Activities
Total loans serviced	29,709,362	27,909,821
Virginia
Loan Sales and Servicing Activities
Total loans serviced	22,531,313	22,115,619
Maryland
Loan Sales and Servicing Activities
Total loans serviced	17,282,260	16,829,320
All other states
Loan Sales and Servicing Activities
Total loans serviced	$ 224,930,524	$ 215,576,909