Quarterly report pursuant to Section 13 or 15(d)

Fair Value - Summary of Mortgage Servicing Rights (Detail)

v3.21.2
Fair Value - Summary of Mortgage Servicing Rights (Detail)
 9 Months Ended 12 Months Ended
Sep. 30, 2021
Dec. 31, 2020
Servicing Assets And Servicing Liabilities At Fair Value Assumptions Used To Estimate Fair Value [Line Items]    
Discount rate 3.00% 3.10%
Mortgage Servicing Rights [Member] | Minimum [Member] | Weighted Average Prepayment Speed [Member]    
Servicing Assets And Servicing Liabilities At Fair Value Assumptions Used To Estimate Fair Value [Line Items]    
Weighted average prepayment speed (CPR) 7.00% 6.60%
Mortgage Servicing Rights [Member] | Minimum [Member] | Weighted average delinquency rate [Member]    
Servicing Assets And Servicing Liabilities At Fair Value Assumptions Used To Estimate Fair Value [Line Items]    
Weighted average delinquency rate 1.20% 1.20%
Mortgage Servicing Rights [Member] | Maximum [Member] | Weighted Average Prepayment Speed [Member]    
Servicing Assets And Servicing Liabilities At Fair Value Assumptions Used To Estimate Fair Value [Line Items]    
Weighted average prepayment speed (CPR) 18.30% 24.90%
Mortgage Servicing Rights [Member] | Maximum [Member] | Weighted average delinquency rate [Member]    
Servicing Assets And Servicing Liabilities At Fair Value Assumptions Used To Estimate Fair Value [Line Items]    
Weighted average delinquency rate 8.90% 9.20%
Mortgage Servicing Rights [Member] | Weighted Average [Member] | Weighted Average Prepayment Speed [Member]    
Servicing Assets And Servicing Liabilities At Fair Value Assumptions Used To Estimate Fair Value [Line Items]    
Weighted average prepayment speed (CPR) 9.50% 12.10%
Mortgage Servicing Rights [Member] | Weighted Average [Member] | Discount rate [Member]    
Servicing Assets And Servicing Liabilities At Fair Value Assumptions Used To Estimate Fair Value [Line Items]    
Discount rate 9.70% 12.10%
Mortgage Servicing Rights [Member] | Weighted Average [Member] | Weighted average delinquency rate [Member]    
Servicing Assets And Servicing Liabilities At Fair Value Assumptions Used To Estimate Fair Value [Line Items]    
Weighted average delinquency rate 1.20% 1.30%