Fair Value Measurements - Additional Information (Detail) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2020 USD ($) Security Loan $ / Loan	Dec. 31, 2019 USD ($) Security $ / Loan
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of bonds owned | Security	12	39
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loan segregated, number of pools | Loan	12
Service costs assumed, per loan | $ / Loan	6.50	6.50
Average PSA assumed rate	292.00%	187.00%
Fair Value, Measurements, Recurring | 100% PSA | Fair Value, Inputs, Level 3 | Between First Month and Month 30
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Prepayment rate increase, each month	0.20%
Fair Value, Measurements, Recurring | Prepayment Rate | 100% PSA | Fair Value, Inputs, Level 3 | First Month
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Prepayment rate	0
Fair Value, Measurements, Recurring | Prepayment Rate | 100% PSA | Fair Value, Inputs, Level 3 | Month 30
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Prepayment rate	6.0
Fair Value, Measurements, Recurring | Prepayment Rate | 100% PSA | Fair Value, Inputs, Level 3 | Thereafter
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Prepayment rate	6.0
Fair Value, Measurements, Recurring | Discount Rate | Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate	12.5	12.5
Mortgage Servicing Rights Assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of residential loan portfolio	2
Corporate bonds | $	$ 774	$ 935
Corporate Bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of bonds owned | Security	6
Corporate bonds | $	$ 2,650	$ 2,650
Corporate Bonds | Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of bonds owned | Security	5
Corporate bonds | $	$ 2,700