Fair Value - Changes in Fair Value, Fair Value Option, Recurring Basis (Details) - Recurring basis - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
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	$ 539	$ 5,338	$ 21,016	$ 11,020
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	539	5,338	21,016	11,020
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	636	3,604	15,158	7,655
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	636	3,604	15,158	7,655
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	(97)	1,734	5,858	3,365
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	(97)	1,734	5,858	3,365
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	534,105	(194,961)	(108,345)	(352,011)
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	739,797	172,752	1,138,515	274,747
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	(205,692)	(367,713)	(1,246,860)	(626,758)
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	739,797	172,752	1,138,515	274,747
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	739,797	172,752	1,138,515	274,747
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	(205,692)	(367,713)	(1,246,860)	(626,758)
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	$ (205,692)	$ (367,713)	$ (1,246,860)	$ (626,758)