Loan Sales and Servicing Activities - Geographical Distribution of Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Loan Sales and Servicing Activities
Total loans serviced	$ 368,684,232	$ 299,293,872
California
Loan Sales and Servicing Activities
Total loans serviced	57,311,867	51,377,441
Florida
Loan Sales and Servicing Activities
Total loans serviced	28,940,696	22,650,926
Texas
Loan Sales and Servicing Activities
Total loans serviced	27,909,821	23,648,042
Virginia
Loan Sales and Servicing Activities
Total loans serviced	22,115,619	19,011,950
Maryland
Loan Sales and Servicing Activities
Total loans serviced	16,829,320	13,774,011
All other states
Loan Sales and Servicing Activities
Total loans serviced	$ 215,576,909	$ 168,831,502