Concentrations of Credit Risk (Details) - Fannie Mae DUS and Freddie Mac TAH Loans - Liabilities - Credit Concentration Risk - USD ($) $ in Billions	6 Months Ended	12 Months Ended
Jun. 30, 2023	Dec. 31, 2022
Concentration Risk
Maximum DB Cayman credit protection	$ 8.6	$ 8.4
California
Concentration Risk
Concentration risk percentage	20.00%	20.00%
Texas
Concentration Risk
Concentration risk percentage	12.00%	11.00%

Maximum amount of loss due to credit risk that, based on the gross fair value of the financial instrument, the entity would incur if parties to the financial instruments that make up the concentration failed completely to perform according to the terms of the contracts and the collateral or other security, if any, for the amount due proved to be of no value to the entity.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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