Fair Value - Changes in Fair Value, Fair Value Option, Recurring Basis (Details) - Recurring basis - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Liabilities.
Net gains (losses) from changes in estimated fair values included in earnings for financial statement items carried at estimated fair value
Total gains (losses) from changes in estimated fair values included in earnings	$ 5,223	$ 20,477
Liabilities. | Net loan servicing fees
Net gains (losses) from changes in estimated fair values included in earnings for financial statement items carried at estimated fair value
Total gains (losses) from changes in estimated fair values included in earnings	5,223	20,477
Excess servicing spread financing
Net gains (losses) from changes in estimated fair values included in earnings for financial statement items carried at estimated fair value
Total gains (losses) from changes in estimated fair values included in earnings	(1,037)	14,522
Excess servicing spread financing | Net loan servicing fees
Net gains (losses) from changes in estimated fair values included in earnings for financial statement items carried at estimated fair value
Total gains (losses) from changes in estimated fair values included in earnings	(1,037)	14,522
Mortgage servicing liabilities
Net gains (losses) from changes in estimated fair values included in earnings for financial statement items carried at estimated fair value
Total gains (losses) from changes in estimated fair values included in earnings	6,260	5,955
Mortgage servicing liabilities | Net loan servicing fees
Net gains (losses) from changes in estimated fair values included in earnings for financial statement items carried at estimated fair value
Total gains (losses) from changes in estimated fair values included in earnings	6,260	5,955
Assets
Net gains (losses) from changes in estimated fair values included in earnings for financial statement items carried at estimated fair value
Total gains (losses) from changes in estimated fair values included in earnings	867,322	(642,450)
Assets | Net gains on loans held for sale at fair value
Net gains (losses) from changes in estimated fair values included in earnings for financial statement items carried at estimated fair value
Total gains (losses) from changes in estimated fair values included in earnings	650,119	398,718
Assets | Net loan servicing fees
Net gains (losses) from changes in estimated fair values included in earnings for financial statement items carried at estimated fair value
Total gains (losses) from changes in estimated fair values included in earnings	217,203	(1,041,168)
Loans held for sale
Net gains (losses) from changes in estimated fair values included in earnings for financial statement items carried at estimated fair value
Total gains (losses) from changes in estimated fair values included in earnings	650,119	398,718
Loans held for sale | Net gains on loans held for sale at fair value
Net gains (losses) from changes in estimated fair values included in earnings for financial statement items carried at estimated fair value
Total gains (losses) from changes in estimated fair values included in earnings	650,119	398,718
Mortgage servicing rights at fair value
Net gains (losses) from changes in estimated fair values included in earnings for financial statement items carried at estimated fair value
Total gains (losses) from changes in estimated fair values included in earnings	217,203	(1,041,168)
Mortgage servicing rights at fair value | Net loan servicing fees
Net gains (losses) from changes in estimated fair values included in earnings for financial statement items carried at estimated fair value
Total gains (losses) from changes in estimated fair values included in earnings	$ 217,203	$ (1,041,168)