Derivative Financial Instruments - Other Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Derivative assets:
Derivative asset, before netting	$ 469,285		$ 469,285		$ 847,831
Netting	(98,016)		(98,016)		(136,593)
Total derivative assets	371,269		371,269		711,238
Derivative liabilities:
Derivative liability, before netting	92,139		92,139		255,360
Netting	(48,229)		(48,229)		(212,722)
Net amounts of liabilities presented in the consolidated balance sheet	43,910		43,910		42,638
Activity for derivative contracts used to hedge the IRLCs and inventory of mortgage loans at notional value
Gains (losses) recognized on derivative financial instruments	91,118	$ (15,764)	(351,033)	$ 1,020,806
Net gains on loans held for sale at fair value | Interest rate lock commitments and loans held for sale
Activity for derivative contracts used to hedge the IRLCs and inventory of mortgage loans at notional value
Gains (losses) recognized on derivative financial instruments	(167,734)	(101,115)	294,804	(326,672)
Net loan servicing fees | Mortgage servicing rights
Activity for derivative contracts used to hedge the IRLCs and inventory of mortgage loans at notional value
Gains (losses) recognized on derivative financial instruments	91,118	(15,764)	(351,033)	1,020,806
Margin Deposits
Derivative assets:
Collateral placed with (received from) derivative counterparties	(49,787)		(49,787)		76,129
Interest rate lock commitments
Derivative assets:
Total derivative assets	344,128		344,128		679,961
Interest rate lock commitments | Net gains on loans held for sale at fair value
Activity for derivative contracts used to hedge the IRLCs and inventory of mortgage loans at notional value
Gains (losses) recognized on derivative financial instruments	5,670	$ 52,871	(333,416)	$ 231,414
Forward contracts | Purchases
Derivative Instruments
Notional amount	24,712,770		24,712,770		31,689,543
Derivative assets:
Derivative asset, before netting	55,765		55,765		133,267
Derivative liabilities:
Derivative liability, before netting	23,274		23,274		1,276
Activity for derivative contracts used to hedge the IRLCs and inventory of mortgage loans at notional value
Balance at beginning of period			31,689,543
Balance at end of period	24,712,770		24,712,770
Forward contracts | Sales
Derivative Instruments
Notional amount	37,785,066		37,785,066		50,438,967
Derivative assets:
Derivative asset, before netting	39,597		39,597		1,451
Derivative liabilities:
Derivative liability, before netting	68,347		68,347		251,149
Activity for derivative contracts used to hedge the IRLCs and inventory of mortgage loans at notional value
Balance at beginning of period			50,438,967
Balance at end of period	37,785,066		37,785,066
MBS put options
Derivative Instruments
Notional amount	11,450,000		11,450,000		12,025,000
Derivative assets:
Derivative asset, before netting	13,106		13,106		14,302
Activity for derivative contracts used to hedge the IRLCs and inventory of mortgage loans at notional value
Balance at beginning of period			12,025,000
Balance at end of period	11,450,000		11,450,000
MBS call options
Derivative Instruments
Notional amount	750,000		750,000
Derivative assets:
Derivative asset, before netting	687		687
Activity for derivative contracts used to hedge the IRLCs and inventory of mortgage loans at notional value
Balance at end of period	750,000		750,000
Swaptions | Purchases
Derivative Instruments
Notional amount	5,455,000		5,455,000		3,375,000
Derivative assets:
Derivative asset, before netting	11,041		11,041		11,939
Activity for derivative contracts used to hedge the IRLCs and inventory of mortgage loans at notional value
Balance at beginning of period			3,375,000
Balance at end of period	5,455,000		5,455,000
Put options on interest rate futures | Purchases
Derivative Instruments
Notional amount	3,450,000		3,450,000		4,750,000
Derivative assets:
Derivative asset, before netting	2,664		2,664		5,520
Activity for derivative contracts used to hedge the IRLCs and inventory of mortgage loans at notional value
Balance at beginning of period			4,750,000
Balance at end of period	3,450,000		3,450,000
Call options on interest rate futures | Purchases
Derivative Instruments
Notional amount	350,000		350,000		850,000
Derivative assets:
Derivative asset, before netting	2,297		2,297		1,391
Activity for derivative contracts used to hedge the IRLCs and inventory of mortgage loans at notional value
Balance at beginning of period			850,000
Balance at end of period	350,000		350,000
Treasury future | Purchases
Derivative Instruments
Notional amount	705,000		705,000		1,065,000
Activity for derivative contracts used to hedge the IRLCs and inventory of mortgage loans at notional value
Balance at beginning of period			1,065,000
Balance at end of period	705,000		705,000
Treasury future | Sales
Derivative Instruments
Notional amount	1,480,000		1,480,000		1,555,000
Activity for derivative contracts used to hedge the IRLCs and inventory of mortgage loans at notional value
Balance at beginning of period			1,555,000
Balance at end of period	1,480,000		1,480,000
Interest rate swap futures | Purchases
Derivative Instruments
Notional amount	4,040,000		4,040,000		4,801,700
Activity for derivative contracts used to hedge the IRLCs and inventory of mortgage loans at notional value
Balance at beginning of period			4,801,700
Balance at end of period	4,040,000		4,040,000
Interest rate swap futures | Sales
Derivative Instruments
Notional amount	250,000		250,000		711,700
Activity for derivative contracts used to hedge the IRLCs and inventory of mortgage loans at notional value
Balance at beginning of period			711,700
Balance at end of period	250,000		250,000
Not designated as hedging instrument | Interest rate lock commitments
Derivative Instruments
Notional amount	13,879,343		13,879,343		20,624,535
Derivative assets:
Derivative asset, before netting	344,128		344,128		679,961
Derivative liabilities:
Derivative liability, before netting	518		518		$ 2,935
Activity for derivative contracts used to hedge the IRLCs and inventory of mortgage loans at notional value
Balance at beginning of period			20,624,535
Balance at end of period	$ 13,879,343		$ 13,879,343