Fair Value - Fair Value Option Maturities, Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Fair value
Total fair value	$ 10,884,506	$ 11,616,400
Recurring basis
Fair value
Total fair value	10,884,506	11,616,400
Loans held for sale | Recurring basis
Fair value
Current through 89 days delinquent	10,526,148	11,304,308
Not in foreclosure	330,472	275,419
In foreclosure	27,886	36,673
Total fair value	10,884,506	11,616,400
Principal amount due upon maturity
Current through 89 days delinquent	10,079,813	10,743,814
Not in foreclosure	327,869	280,595
In foreclosure	31,253	39,529
Total principal amount due upon maturity	10,438,935	11,063,938
Difference
Current through 89 days delinquent	446,335	560,494
Not in foreclosure	2,603	(5,176)
In foreclosure	(3,367)	(2,856)
Total difference	$ 445,571	$ 552,462