Fair Value - Fair Value Option Maturities, Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Fair value
Total fair value	$ 9,126,172	$ 4,912,953
Recurring basis
Fair value
Total fair value	9,126,172	4,912,953
Loans held for sale | Recurring basis
Fair value
Current through 89 days delinquent	8,670,895	4,628,333
Not in foreclosure	392,866	236,650
In foreclosure	62,411	47,970
Total fair value	9,126,172	4,912,953
Principal amount due upon maturity
Current through 89 days delinquent	8,279,163	4,431,854
Not in foreclosure	404,183	241,958
In foreclosure	66,327	50,194
Total principal amount due upon maturity	8,749,673	4,724,006
Difference
Current through 89 days delinquent	391,732	196,479
Not in foreclosure	(11,317)	(5,308)
In foreclosure	(3,916)	(2,224)
Total difference	$ 376,499	$ 188,947