SEC Schedule, Article 12-29, Mortgage Loans on Real Estate (Policies)	3 Months Ended
	Mar. 31, 2021
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Abstract]
Finance, Loan and Lease Receivables, Held-for-investment, Allowance and Nonperforming Loans, Policy	For loans not subject to the COVID-19-related nonaccrual policy, we discontinue accruing interest when we believe collectability of principal and interest is not reasonably assured, which for a single-family loan we have determined, based on our historical experience, to be when the loan becomes two months or more past due according to its contractual terms. Interest previously accrued but not collected on such loans is reversed through interest income at the date the loan is placed on nonaccrual status. For single-family loans on nonaccrual status, we recognize income when cash payments are received. We return a non-modified single-family loan to accrual status at the point when the borrower brings the loan current. We return a modified single-family loan to accrual status at the point when the borrower has successfully made all required payments during the trial period (generally three to four months) and the modification is made permanent. We place a multifamily loan on nonaccrual status when the loan becomes two months or more past due according to its contractual terms unless the loan is well secured such that collectability of principal and accrued interest is reasonably assured. For multifamily loans on nonaccrual status, we apply any payment received on a cost recovery basis to reduce principal on the mortgage loan. We return a multifamily loan to accrual status when the borrower cures the delinquency of the loan. Single-family and multifamily loans are reported past due if a full payment of principal and interest is not received within one month of its due date.For loans negatively impacted by the COVID-19 pandemic, we continue to recognize interest income at the current contractual yield for up to six months of delinquency provided that the loan was either current at March 1, 2020 or originated after March 1, 2020, and collection of principal and interest is reasonably assured. For single-family loans where we have provided relief beyond six months of delinquency, we continue to accrue interest income provided that the loan remains in a forbearance arrangement and collection of principal and interest continues to be reasonably assured. Multifamily loans that are in a forbearance arrangement are placed on nonaccrual status when the borrower is six months past due unless the loan is both well secured and in the process of collection. Loans that have been placed in a repayment plan or that have been brought current through a modification or a payment deferral are returned to accrual status once the borrower has made six consecutive contractual payments under the terms of the repayment plan or the modified loan. For loans in a forbearance arrangement that are placed on nonaccrual status, cash payments for interest are applied as a reduction of accrued interest receivable until the receivable has been reduced to zero, and then recognized as interest income. If a loan is modified, any capitalized interest that has not been previously recognized as interest income is recorded as a discount to the loan and amortized over the life of the loan.