Fair Value - Level 3 Input Roll Forward, Recurring Basis (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Roll forward of liabilities measured using Level 3 inputs on a recurring basis
Mortgage servicing liabilities resulting from loan sales	$ 6,962	$ 6,576
Recurring basis
Roll forward of assets measured using Level 3 inputs on a recurring basis
Balance at the beginning of the period		3,455,505
Purchases and issuances, net		2,008,971
Capitalization of interest and advances		18,027
Sales and repayments		(738,928)
Mortgage servicing rights resulting from loan sales		282,315
Changes in fair value included in income arising from:
Changes in instrument specific credit risk		(7,523)
Other factors		(841,250)
Total changes in fair value included in income		(848,773)
Transfers from mortgage loans held for sale from Level 3 to Level 2		(489,407)
Transfers to real estate acquired in settlement of loans		(691)
Transfers from interest rate lock commitments to loans held for sale		(363,354)
Balance at the end of the period		3,323,665
Changes in fair value recognized during the period relating to assets still held at the end of the period		(737,830)
Roll forward of liabilities measured using Level 3 inputs on a recurring basis
Balance at the beginning of the period	177,074	207,726
Issuances	557	379
Accrual of interest on excess servicing spread financing	1,280	1,974
Repayment		(9,308)
Settlement	(134,624)
Mortgage servicing liabilities resulting from loan sales	6,962	6,576
Changes in fair value included in income	(5,223)	(20,477)
Balance at the end of the period	46,026	186,870
Changes in fair value recognized during the period relating to liability still outstanding at the end of the period	(6,260)	(20,477)
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 period	131,750	178,586
Issuances	557	379
Accrual of interest on excess servicing spread financing	1,280	1,974
Repayment		(9,308)
Settlement	(134,624)
Changes in fair value included in income	1,037	(14,522)
Balance at the end of the period		157,109
Changes in fair value recognized during the period relating to liability still outstanding at the end of the period		(14,522)
Recurring basis | Mortgage servicing liabilities
Roll forward of liabilities measured using Level 3 inputs on a recurring basis
Balance at the beginning of the period	45,324	29,140
Mortgage servicing liabilities resulting from loan sales	6,962	6,576
Changes in fair value included in income	(6,260)	(5,955)
Balance at the end of the period	46,026	29,761
Changes in fair value recognized during the period relating to liability still outstanding at the end of the period	(6,260)	(5,955)
Recurring basis | Loans held for sale
Roll forward of assets measured using Level 3 inputs on a recurring basis
Balance at the beginning of the period	4,675,169	383,878
Purchases and issuances, net	4,156,681	1,641,231
Capitalization of interest and advances	90,165	18,027
Sales and repayments	(928,901)	(738,928)
Changes in fair value included in income arising from:
Changes in instrument specific credit risk	48,154	(7,523)
Total changes in fair value included in income	48,154	(7,523)
Transfers from mortgage loans held for sale from Level 3 to Level 2	(2,839,121)	(489,407)
Transfers to real estate acquired in settlement of loans	(82)	(691)
Balance at the end of the period	5,202,065	806,587
Changes in fair value recognized during the period relating to assets still held at the end of the period	104,132	(11,856)
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 period	677,026	136,650
Purchases and issuances, net	477,933	341,980
Changes in fair value included in income arising from:
Other factors	(179,613)	199,918
Total changes in fair value included in income	(179,613)	199,918
Transfers from interest rate lock commitments to loans held for sale	(637,406)	(363,354)
Balance at the end of the period	337,940	315,194
Changes in fair value recognized during the period relating to assets still held at the end of the period	337,940	315,194
Recurring basis | Repurchase agreement derivatives
Roll forward of assets measured using Level 3 inputs on a recurring basis
Balance at the beginning of the period	2,581,174	8,187
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 period	3,268,910	8,187
Changes in fair value recognized during the period relating to assets still held at the end of the period	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 period	7,933,369	2,926,790
Purchases and issuances, net	4,634,614	25,760
Capitalization of interest and advances	90,165
Sales and repayments	(928,901)
Mortgage servicing rights resulting from loan sales	470,533	282,315
Changes in fair value included in income arising from:
Changes in instrument specific credit risk	48,154
Other factors	37,590	(1,041,168)
Total changes in fair value included in income	85,744	(1,041,168)
Transfers from mortgage loans held for sale from Level 3 to Level 2	(2,839,121)
Transfers to real estate acquired in settlement of loans	(82)
Transfers from interest rate lock commitments to loans held for sale	(637,406)
Balance at the end of the period	8,808,915	2,193,697
Changes in fair value recognized during the period relating to assets still held at the end of the period	$ 659,275	$ (1,041,168)