Quarterly report pursuant to Section 13 or 15(d)

Fair Value - Summary of Commercial Mortgage Portfolio Lending (Detail)

v3.21.2
Fair Value - Summary of Commercial Mortgage Portfolio Lending (Detail) - Commercial Mortgage Portfolio Lending [Member]
6 Months Ended 12 Months Ended
Jun. 30, 2021
Dec. 31, 2020
Minimum [Member] | Prepayment Rate [Member]    
Fair Value Portfolio Mortgage Loans Classified Under Mortgage Loans Held For Sale Measured On Recurring And Nonrecurring Basis Fair Value Measurement [Line Items]    
Prepayment rate (CPR) 0.00% 0.00%
Minimum [Member] | Default Rate [Member]    
Fair Value Portfolio Mortgage Loans Classified Under Mortgage Loans Held For Sale Measured On Recurring And Nonrecurring Basis Fair Value Measurement [Line Items]    
Default rate (CDR) 1.00% 1.00%
Maximum [Member] | Prepayment Rate [Member]    
Fair Value Portfolio Mortgage Loans Classified Under Mortgage Loans Held For Sale Measured On Recurring And Nonrecurring Basis Fair Value Measurement [Line Items]    
Prepayment rate (CPR) 14.80% 15.00%
Maximum [Member] | Default Rate [Member]    
Fair Value Portfolio Mortgage Loans Classified Under Mortgage Loans Held For Sale Measured On Recurring And Nonrecurring Basis Fair Value Measurement [Line Items]    
Default rate (CDR) 27.10% 42.70%
Weighted Average [Member] | Prepayment Rate [Member]    
Fair Value Portfolio Mortgage Loans Classified Under Mortgage Loans Held For Sale Measured On Recurring And Nonrecurring Basis Fair Value Measurement [Line Items]    
Prepayment rate (CPR) 8.10% 9.30%
Weighted Average [Member] | Measurement Input, Discount Rate [Member]    
Fair Value Portfolio Mortgage Loans Classified Under Mortgage Loans Held For Sale Measured On Recurring And Nonrecurring Basis Fair Value Measurement [Line Items]    
Discount rate 3.80% 4.90%
Weighted Average [Member] | Default Rate [Member]    
Fair Value Portfolio Mortgage Loans Classified Under Mortgage Loans Held For Sale Measured On Recurring And Nonrecurring Basis Fair Value Measurement [Line Items]    
Default rate (CDR) 1.70% 2.00%