Fair Value - Key Assumptions Used in Determining Fair Value of MSRs at Time of Initial Recognition (Detail) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024 USD ($) UsdPerLoan	Jun. 30, 2023 USD ($) UsdPerLoan	Jun. 30, 2024 USD ($) UsdPerLoan	Jun. 30, 2023 USD ($) UsdPerLoan
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, MSR recognized | $	$ 40,619	$ 90,747	$ 71,868	$ 191,365
Fair value, Unpaid principal balance of underlying loans | $	$ 2,242,511	$ 4,856,301	$ 4,073,529	$ 10,405,626
Fair value, Weighted-average annual servicing fee rate (in basis points)	0.35%	0.39%	0.35%	0.40%
Minimum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value inputs, Pricing spread during period	10.80%	11.80%	10.80%	11.80%
Fair Value inputs, Prepayment speed during period	5.90%	5.50%	5.50%	5.50%
Fair Value inputs, Weighted average equivalent average life during period	3 years 4 months 24 days	2 years 10 months 24 days	3 years 4 months 24 days	2 years 9 months 18 days
Fair Value inputs, Annual per loan cost of servicing during period	69	68	69	68
Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value inputs, Pricing spread during period	17.80%	20.20%	17.80%	21.80%
Fair Value inputs, Prepayment speed during period	8.10%	8.80%	8.50%	8.80%
Fair Value inputs, Weighted average equivalent average life during period	7 years 2 months 12 days	7 years 1 month 6 days	7 years 2 months 12 days	7 years 1 month 6 days
Fair Value inputs, Annual per loan cost of servicing during period	87	69	87	69
Weighted Average [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value inputs, Pricing spread during period	6.00%	5.90%	5.80%	5.90%
Fair Value inputs, Prepayment speed during period	11.50%	11.90%	12.40%	12.60%
Fair Value inputs, Weighted average equivalent average life during period	7 years 1 month 6 days	7 years	6 years 9 months 18 days	6 years 8 months 12 days
Fair Value inputs, Annual per loan cost of servicing during period	69	69	70	69