Fair Value - Level 3 Input Roll Forward, Recurring Basis (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Roll forward of liabilities measured using Level 3 inputs on a recurring basis
Mortgage servicing liabilities resulting from loan sales		$ 6,962
Changes in fair value included in income		(1,037)
Recurring basis
Roll forward of assets measured using Level 3 inputs on a recurring basis
Balance at the beginning of the year	$ 5,329,147	7,933,369
Purchases and issuances, net	2,296,087	4,634,614
Capitalization of interest and advances	32,111	90,165
Sales and repayments	(1,134,992)	(928,901)
Mortgage servicing rights resulting from loan sales	616,302	470,533
Mortgage servicing rights resulting from change in method of accounting		6,962
Changes in fair value included in income arising from:
Changes in instrument specific credit risk	(5,816)	48,154
Other factors	(199,114)	37,590
Total changes in fair value included in income	(204,930)	85,744
Transfers from mortgage loans held for sale from Level 3 to Level 2	(1,365,971)	(2,839,121)
Transfers to real estate acquired in settlement of loans	(82)
Transfers from interest rate lock commitments to loans held for sale	(46,226)	(637,406)
Balance at the end of the year	5,521,528	8,808,915
Changes in fair value recognized during the period relating to assets still held at the end of the year	233,466	659,275
Roll forward of liabilities measured using Level 3 inputs on a recurring basis
Balance at the beginning of the year		177,074
Issuances		557
Accrual of interest on excess servicing spread financing		1,280
Repayment		(134,624)
Changes in fair value included in income		(5,223)
Balance at the end of the year		46,026
Changes in fair value recognized during the period relating to liability still outstanding at the end of the year		(6,260)
Recurring basis | Excess servicing spread financing
Roll forward of liabilities measured using Level 3 inputs on a recurring basis
Balance at the beginning of the year	2,816	131,750
Issuances		557
Accrual of interest on excess servicing spread financing		1,280
Repayment		(134,624)
Changes in fair value included in income	(252)	1,037
Balance at the end of the year	2,564
Changes in fair value recognized during the period relating to liability still outstanding at the end of the year	(252)
Recurring basis | Mortgage servicing liabilities
Roll forward of assets measured using Level 3 inputs on a recurring basis
Mortgage servicing rights resulting from change in method of accounting		6,962
Roll forward of liabilities measured using Level 3 inputs on a recurring basis
Balance at the beginning of the year		45,324
Changes in fair value included in income		(6,260)
Balance at the end of the year		46,026
Changes in fair value recognized during the period relating to liability still outstanding at the end of the year		(6,260)
Recurring basis | Mortgage loans held for sale
Roll forward of assets measured using Level 3 inputs on a recurring basis
Balance at the beginning of the year	1,128,876	4,675,169
Purchases and issuances, net	2,134,778	4,156,681
Capitalization of interest and advances	32,111	90,165
Sales and repayments	(1,134,992)	(928,901)
Changes in fair value included in income arising from:
Changes in instrument specific credit risk	(5,816)	48,154
Other factors	(12,396)
Total changes in fair value included in income	(18,212)	48,154
Transfers from mortgage loans held for sale from Level 3 to Level 2	(1,365,971)	(2,839,121)
Transfers to real estate acquired in settlement of loans	(82)
Balance at the end of the year	776,590	5,202,065
Changes in fair value recognized during the period relating to assets still held at the end of the year	(17,092)	104,132
Recurring basis | Interest rate lock commitments
Roll forward of assets measured using Level 3 inputs on a recurring basis
Balance at the beginning of the year	322,193	677,026
Purchases and issuances, net	161,309	477,933
Changes in fair value included in income arising from:
Other factors	(399,377)	(179,613)
Total changes in fair value included in income	(399,377)	(179,613)
Transfers from interest rate lock commitments to loans held for sale	(46,226)	(637,406)
Balance at the end of the year	37,899	337,940
Changes in fair value recognized during the period relating to assets still held at the end of the year	37,899	337,940
Recurring basis | Repurchase agreement derivatives
Roll forward of assets measured using Level 3 inputs on a recurring basis
Balance at the beginning of the year		2,581,174
Mortgage servicing rights resulting from loan sales		470,533
Changes in fair value included in income arising from:
Other factors		217,203
Total changes in fair value included in income		217,203
Balance at the end of the year		3,268,910
Changes in fair value recognized during the period relating to assets still held at the end of the year		$ 217,203
Recurring basis | Mortgage servicing rights
Roll forward of assets measured using Level 3 inputs on a recurring basis
Balance at the beginning of the year	3,878,078
Mortgage servicing rights resulting from loan sales	616,302
Changes in fair value included in income arising from:
Other factors	212,659
Total changes in fair value included in income	212,659
Balance at the end of the year	4,707,039
Changes in fair value recognized during the period relating to assets still held at the end of the year	$ 212,659