Fair Value Measurements - Schedule of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage loans at fair value	$ 5,208,167	$ 17,473,324
Investment securities at fair value, pledged	138,417	152,263
Total assets	9,102,618	21,007,895
Public and Private Warrants	5,324	9,456
Total liabilities	120,754	46,197
IRLCs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	9,511	24,899
Derivative liability	108,475	11,138
FLSCs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	232,421	42,457
Derivative liability	6,955	25,603
Mortgage servicing rights
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage servicing rights	3,514,102	3,314,952	$ 2,300,434	$ 1,760,304
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage loans at fair value	0	0
Investment securities at fair value, pledged	0	0
Total assets	0	0
Public and Private Warrants	4,038	6,286
Total liabilities	4,038	6,286
Level 1 | IRLCs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	0	0
Derivative liability	0	0
Level 1 | FLSCs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	0	0
Derivative liability	0	0
Level 1 | Mortgage servicing rights
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage servicing rights	0	0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage loans at fair value	5,208,167	17,473,324
Investment securities at fair value, pledged	138,417	152,263
Total assets	5,579,005	17,668,044
Public and Private Warrants	1,286	3,170
Total liabilities	8,241	28,773
Level 2 | IRLCs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	0	0
Derivative liability	0	0
Level 2 | FLSCs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	232,421	42,457
Derivative liability	6,955	25,603
Level 2 | Mortgage servicing rights
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage servicing rights	0	0
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage loans at fair value	0	0
Investment securities at fair value, pledged	0	0
Total assets	3,523,613	3,339,851
Public and Private Warrants	0	0
Total liabilities	108,475	11,138
Level 3 | IRLCs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	9,511	24,899
Derivative liability	108,475	11,138
Level 3 | FLSCs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	0	0
Derivative liability	0	0
Level 3 | Mortgage servicing rights
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage servicing rights	$ 3,514,102	$ 3,314,952