Fair Value - Level 3 Input Roll Forward, Recurring Basis (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Roll forward of liabilities measured using Level 3 inputs on a recurring basis
Mortgage servicing liabilities resulting from loan sales			$ 64,383	$ 6,576
Recurring basis
Roll forward of assets measured using Level 3 inputs on a recurring basis
Balance at the beginning of the period	$ 8,808,915	$ 3,323,665	7,933,369	3,455,505
Purchases and issuances, net	7,180,028	785,005	11,886,402	2,793,976
Capitalization of interest and advances	60,439	14,994	78,844	33,021
Sales and repayments	(3,866,340)	(60,364)	(4,795,241)	(799,292)
Mortgage servicing rights resulting from loan sales	483,362	225,534	953,895	507,849
Changes in fair value included in income arising from:
Changes in instrument specific credit risk	179,792	1,132	227,946	(6,391)
Other factors	(7,189)	91,506	30,401	(749,744)
Total changes in fair value included in income	172,603	92,638	258,347	(756,135)
Transfers from mortgage loans held for sale from Level 3 to Level 2	(4,585,789)	(389,486)	(7,424,910)	(878,893)
Transfers to real estate acquired in settlement of loans			(82)	(691)
Transfers from interest rate lock commitments to loans held for sale	(678,699)	(740,477)	(1,316,105)	(1,103,831)
Balance at the end of the period	7,574,519	3,251,509	7,574,519	3,251,509
Changes in fair value recognized during the period relating to assets still held at the end of the period	78,170	161,655	357,012	(879,359)
Roll forward of liabilities measured using Level 3 inputs on a recurring basis
Balance at the beginning of the period		186,870	177,074	207,726
Issuances		483	557	862
Accrual of interest on excess servicing spread financing		2,372	1,280	4,346
Repayment		(8,122)	(134,624)	(17,430)
Mortgage servicing liabilities resulting from loan sales			64,383	6,576
Changes in fair value included in income		(539)	(8,579)	(21,016)
Balance at the end of the period	100,091	181,064	100,091	181,064
Changes in fair value recognized during the period relating to liability still outstanding at the end of the period		(539)	(9,616)	(21,016)
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	46,026	157,109	131,750	178,586
Issuances		483	557	862
Accrual of interest on excess servicing spread financing		2,372	1,280	4,346
Repayment		(8,122)	(134,624)	(17,430)
Mortgage servicing liabilities resulting from loan sales	57,421
Changes in fair value included in income	(3,356)	(636)	1,037	(15,158)
Balance at the end of the period	100,091	151,206	100,091	151,206
Changes in fair value recognized during the period relating to liability still outstanding at the end of the period	(3,356)	(636)		(15,158)
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		29,761	45,324	29,140
Mortgage servicing liabilities resulting from loan sales			64,383	6,576
Changes in fair value included in income		97	(9,616)	(5,858)
Balance at the end of the period	100,091	29,858	100,091	29,858
Changes in fair value recognized during the period relating to liability still outstanding at the end of the period		97	(9,616)	(5,858)
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	5,202,065	806,587	4,675,169	383,878
Purchases and issuances, net	6,828,094	288,856	11,056,535	1,930,087
Capitalization of interest and advances	60,439	14,994	78,844	33,021
Sales and repayments	(3,866,340)	(60,364)	(4,795,241)	(799,292)
Changes in fair value included in income arising from:
Changes in instrument specific credit risk	179,792	1,132	227,946	(6,391)
Total changes in fair value included in income	179,792	1,132	227,946	(6,391)
Transfers from mortgage loans held for sale from Level 3 to Level 2	(4,585,789)	(389,486)	(7,424,910)	(878,893)
Transfers to real estate acquired in settlement of loans			(82)	(691)
Balance at the end of the period	3,818,261	661,719	3,818,261	661,719
Changes in fair value recognized during the period relating to assets still held at the end of the period	74,184	(717)	135,823	(563)
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	337,940	315,194	677,026	136,650
Purchases and issuances, net	351,934	496,149	829,867	838,129
Changes in fair value included in income arising from:
Other factors	332,435	297,198	152,822	497,116
Total changes in fair value included in income	332,435	297,198	152,822	497,116
Transfers from interest rate lock commitments to loans held for sale	(678,699)	(740,477)	(1,316,105)	(1,103,831)
Balance at the end of the period	343,610	368,064	343,610	368,064
Changes in fair value recognized during the period relating to assets still held at the end of the period	343,610	368,064	343,610	368,064
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		8,187		8,187
Changes in fair value included in income arising from:
Balance at the end of the period		8,187		8,187
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	3,268,910	2,193,697	2,581,174	2,926,790
Purchases and issuances, net				25,760
Mortgage servicing rights resulting from loan sales	483,362	225,534	953,895	507,849
Changes in fair value included in income arising from:
Other factors	(339,624)	(205,692)	(122,421)	(1,246,860)
Total changes in fair value included in income	(339,624)	(205,692)	(122,421)	(1,246,860)
Balance at the end of the period	3,412,648	2,213,539	3,412,648	2,213,539
Changes in fair value recognized during the period relating to assets still held at the end of the period	$ (339,624)	$ (205,692)	$ (122,421)	$ (1,246,860)